JP5196810B2 - Side-light leakage type illumination device provided with sheet-like optical transmission body and method for manufacturing the same - Google Patents

Description

The present invention relates to a side light leakage type illumination device and a manufacturing how having a sheet-like optical transmission medium having a soft flexible.

  Plastic optical transmission bodies are advantageous in lighting applications, sensor applications, and communication applications because they have advantages such as easy end face processing and handling, low cost and light weight, and large diameters. In particular, a plastic light transmission body has a feature that it does not transmit electricity or heat, and since it becomes an illumination device simply by being combined with a light source device and is easy to construct, it has been often used in lighting applications in recent years.

  For lighting applications, illuminate in a line shape to detect pinholes in sheets and paper, or illuminate in a flat shape like the backlight of a personal computer display, keyboard, mobile phone screen, liquid crystal panel, or touch control panel. There are uses to do. Therefore, recently, there is an increasing demand for a plastic optical transmission body (illumination medium) that can illuminate a wide range and has flexibility and flexibility.

  Many proposals have been made so far for sheet-like light transmission bodies (illumination media) and methods for producing the same.

  For example, Patent Document 1 proposes a light detection device using a light guide obtained by processing one sheet-like light guide material (for example, a transparent acrylic plate).

  In Patent Document 2 and Patent Document 3, a plurality of optical fiber cores formed by coating a plastic optical fiber (POF) having a core and a clad are arranged in parallel, and the plurality of optical fiber core wires are collectively reacted. There has been proposed a tape-type optical fiber core wire having a protective coating made of a curable silicone-based cured resin.

  Patent Document 4 proposes a sheet-like POF formed by thermocompression bonding a plurality of POFs in a closely parallel state.

  Patent Document 5 proposes a planar light-emitting illumination device in which light from a light-emitting diode (LED) is input from the side surface of a transmissive material that transmits planar light.

Patent Document 6 and Patent Document 7 include a sheet-type optical path in which a clad portion is formed by applying a coating solution in which transparent resin beads are dissolved in an organic solvent to an acrylic resin sheet or the like as a core portion (dip coating method). Proposed.
JP-A 63-236025 JP-A-6-201957 JP 2000-121898 A JP-A-6-317716 JP 2004-186124 A JP-A-2005-340160 Japanese Patent Laying-Open No. 2005-300672

  The light guide part of the light guide described in Patent Document 1 is composed only of a core part, and uses an air layer as a cladding. However, in this type of light guide, if the side surface of the light guide is scratched, the light leaks from that portion or the transmitted light actually oozes out from the core portion. Therefore, the distance that light can be transmitted is very short, and it is difficult to apply it to lighting applications.

  In order to manufacture the sheet-like POF described in Patent Document 2, Patent Document 3 and Patent Document 4, it is necessary to further bundle POF strands prepared in advance into a sheet shape, Processing man-hours increase. Furthermore, since each POF strand is separated by a clad, in order to illuminate the entire sheet uniformly, it is necessary to make light incident uniformly on all the POF strands, resulting in a large number of parts and processing steps. Become. Furthermore, since the POF strands are arranged, the area of the core portion is reduced and the amount of received light is reduced.

  In patent document 5, only glass is described as a member which comprises a planar light-emitting body. Therefore, this flat light emitter does not have soft flexibility. In addition, since the mirror surface processing is required in the subsequent process in order to form the reflection surface that functions as the cladding, the number of steps is increased.

  In the sheet type optical path manufactured by the dip coating method described in Patent Document 6 and Patent Document 7, it is difficult to control the thickness of the clad uniformly, and the organic solvent used for the clad coating liquid is the core solvent. The material may dissolve. As a result, when this is used for lighting applications, unevenness in the amount of light occurs or the light transmission performance is insufficient. Therefore, it is difficult to apply this dip coating method to the manufacture of a sheet type optical path having a small sheet thickness. Furthermore, the dip coating method requires coating, drying, and curing processes, and increases the number of processing steps.

An object of the present invention, the flexible flexible and excellent uniformity light leakage resistance and light quantity, further inexpensively side light leakage type illumination device having a sheet-like optical transmission member which can be manufactured and a manufacturing how Is to provide.

  As a result of intensive studies in view of the above problems, the present inventors have found that a specific sheet-like optical transmission body obtained by a specific manufacturing method solves the above problems.

That is, the present invention
A side light leakage type illumination device having a sheet-like light transmission body and a light source device optically connected to at least one end of the sheet-like light transmission body,
The sheet-like light transmission body is a flexible and flexible sheet-like light transmission body in which the upper and lower surfaces of a planar core portion made of a transparent organic polymer are covered with at least one clad portion,
The core portion of the sheet-like optical transmission body is composed of a methyl methacrylate homopolymer or copolymer, a polystyrene resin, a polycarbonate resin, or a cyclic polyolefin resin,
The clad portion of the sheet-like optical transmission body is made of a fluorinated methacrylate polymer or a vinylidene fluoride polymer,
When the sheet width of the sheet-like optical transmission body is L (mm) and the sheet thickness is d (mm), the following formula (1)
10 ≦ L / d ≦ 10000, 0.1 ≦ d ≦ 1.0 (1)
When the thickness of the clad part is b (mm), the following formulas (2) and (3)
b ≦ d / 2−0.01 (2)
0.005 ≦ b ≦ 0.1 (3)
The filled, left and right side end faces of the core portion is not covered with the cladding portion, and, Ri surface roughness Ra der less 1μm measured according to JIS B0601 of the left and right side end faces of the sheet-shaped optical transmission medium,
At the molding temperature of the sheet-form optical transmission body, the amount (g) of the polymer discharged in 10 minutes from a nozzle having a diameter of 2 mm and a length of 8 mm under the condition of a load of 5 kgf (49 N) was defined as a melt flow rate (MFR). When the MFR (M ₁ ) of the material of the core part and the MFR (M ₂ ) of the material of the cladding part have a relationship of M ₁ <M ₂ ,
When the shear viscosity of the material of the core portion is η _A (Pa · s) and the shear viscosity of the material of the cladding portion is η _B (Pa · s) at the molding temperature of the sheet-like optical transmission body , the shear rate is 20 The shear viscosity ratio η _A / η _{B in} the region of / s to 10000 / s is represented by the following formula (4)
_{1.0 <η A / η B ≦} 6.0 (4)
The filling,
Cladding portion of the sheet-like light transmission body, side light leakage type crystal melting heat in the differential scanning calorimetry (DSC) and wherein the Ru consists vinylidene fluoride polymer in the range of 10 to 80 mJ / mg Illumination device.

The present invention further provides a method for manufacturing a side light leakage type illumination device, molding melted raw extrusion by the molding interest over preparative type optical transmission body using a die having a slit-shaped discharge opening, A step of manufacturing the sheet-like optical transmission body by cleaving the clad portions at both ends of the sheet-like optical transmission body after forming the sheet, and optically connecting a light source device to at least one end of the sheet-like optical transmission body It is a manufacturing method of the side light leakage type illumination device characterized by having a process .

  Furthermore, the present invention is an illumination device having the sheet-like light transmission body and a light source device optically connected to at least one end of the sheet-like light transmission body, and a part of a side surface of the sheet-like light transmission body A side light leakage type illumination device characterized in that light is leaked to the outside from the roughened portion or the portion from which the cladding portion is removed.

The sheet-like optical transmission body of the side-light-separating type illumination device of the present invention can be manufactured at a low cost, has flexibility and flexibility, and is excellent in translucency. In addition, according to the method for manufacturing a side -light-transmitting illumination device of the present invention, it is possible to manufacture a sheet-like optical transmission body having excellent characteristics at a low cost. Further, the side light leakage type illumination device of the present invention has a large irradiation light amount, little light scattering on the side end surface of the sheet, uniform light leakage on the illumination surface, and the device can be reduced in size and weight. is there.

  1 and 3 are a schematic cross-sectional view and a perspective view of a sheet-like optical transmission body of the present invention.

  In the sheet-like optical transmission body, the upper and lower surfaces of the sheet-like core portion 1 are covered with at least one clad portion 2 and the left and right end surfaces of the core portion 1 are not covered with the clad portion.

This sheet-form optical transmission body is represented by the following formula (1), where the sheet width of the sheet-form optical transmission body is L (mm) and the sheet thickness is d (mm).
5 ≦ L / d ≦ 40000, 0.05 ≦ d ≦ 1.0 (1)
Meet. Further, the lower limit of L / d is preferably 7 (mm), and more preferably 10 (mm). The upper limit of L / d is preferably 10,000 (mm), more preferably 1000 (mm). The lower limit of d is preferably 0.1 (mm), and more preferably 0.2 (mm). The upper limit of d is preferably 0.8 (mm). The lower limit value of d is significant in terms of the strength of the sheet-like optical transmission body, and the upper limit value of d is significant in terms of flexibility and flexibility. The lower limit value of L / d is significant in terms of suppressing light leakage at the side end surface, maintaining a sufficient amount of light up to the sheet end surface, and light leakage uniformity, and as a result, enables irradiation over a wide range. The upper limit value of L / d is significant in terms of the uniformity of the amount of light in the vicinity of the light incident portion or the uniformity of light leakage.

FIG. 2 is a graph showing the range of sheet thickness and clad thickness of the sheet-like optical transmission body. In this sheet-like optical transmission body, when the thickness of the cladding portion 2 is b (mm) and the sheet thickness is d (mm), the following formula (2)
b ≦ d / 2−0.01 (2)
Meet. Furthermore, while satisfy | filling said Formula (2), it is preferable to satisfy | fill following Formula (6) as shown in FIG. .

0.05 ≦ d ≦ 1.0 and 0.002 ≦ b ≦ 0.25 (6)
0.1 ≦ d ≦ 0.9 and 0.005 ≦ b ≦ 0.1 (7)
0.2 ≦ d ≦ 0.8 and 0.01 ≦ b ≦ 0.05 (8)
The above formula (2) is significant in terms of transmitting a sufficient amount of light. The lower limit value of d in the above formulas (6) to (8) is significant in terms of the stability of extrusion when producing a sheet-like optical transmission body. The upper limit of d is significant in terms of flexibility and flexibility. The lower limit of b is significant in terms of suppressing light leakage from the cladding. The upper limit of b is significant in terms of prevention of attenuation of light leakage from the clad portion, maintenance of light leakage on the side surface, manufacturing cost, and the like.

  In the sheet-like optical transmission body shown in FIGS. 1 and 3, no clad portion is formed on the left and right end faces 3 (shaded portions in FIG. 3), and the both end faces 3 are sufficiently smooth. . If clad portions are present on both side end surfaces 3, the luminance at the side end portions may become higher than the luminance at the center of the sheet when light is incident, which may cause a problem in use as an illuminating body. May occur. In addition, if there are clad portions on both side end surfaces 3, the thickness of both side end portions 3 may be larger than the thickness of the center portion of the sheet. In this case, if a roughening process is performed on both sides of the sheet as will be described later, there may be a problem in process passability. In the present invention, since the clad portions are not present on both side end surfaces 3, such a problem does not occur.

  As a method of preventing the clad portions from being provided on both side end faces 3, for example, when forming a sheet-shaped optical transmission body having a multilayer sheet structure with a T-die extrusion device, the core portion and the clad portion are separately formed into a sheet shape in advance. There is a method of extruding and then bonding the two together. Also, for example, a sheet-like optical transmission body having a shape in which the outer periphery of the core part is completely covered with the clad part is formed, and then only the clad parts on both the left and right end parts are slit cutters, diamond cutters, water jet cutters, air jet cutters. There is a method of cutting using a known cutting means such as. However, it is not limited to these methods.

  When the smoothness of both side end surfaces 3 of the sheet-like optical transmission body is not sufficient, light reflection or refraction occurs on both side end surfaces 3, resulting in a problem that the luminance partially increases. There is a fear. However, since both side end surfaces 3 in the sheet-like optical transmission body of the present invention are smooth surfaces having a surface roughness Ra of 1 μm or less, such a problem does not occur. The surface roughness Ra is a center line average roughness measured according to JIS B0601. Furthermore, the surface roughness Ra is preferably 0.5 μm or less, and more preferably 0.1 μm or less. Each of these ranges is significant in terms of uniform luminance distribution. The method for setting the surface roughness Ra to 1 μm or less is not particularly limited, but after forming the sheet-like optical transmission body, the conditions for cutting the clad portions at the left and right ends, and the cutting of the left and right ends are finished. What is necessary is just to select suitably the conditions at the time of grind | polishing the part according to a well-known method.

When the melt flow rate (MFR) is defined as the amount (g) of polymer discharged in 10 minutes from a nozzle having a diameter of 2 mm and a length of 8 mm under a load of 5 kgf (49 N) at the molding temperature of the sheet-like optical transmission body. , MFR of the core portion material MFR of (M ₁₎ and the cladding portion of the material (M ₂₎ is preferably in the relationship of M ₁ <M _2. Here, the molding temperature means the temperature of the slit die. Such a relationship is significant in terms of the ease of forming the multilayer sheet shape, the shape control of the end of the core portion, the ease of forming a thin and uniform clad portion, and the like.

In order to make the sheet shape of the sheet-shaped optical transmission body uniform, it is important to control the relationship between the shear viscosity η of the core material and the clad material at the molding temperature within a certain range. For example, when the shear viscosity of the core material is η _A (Pa · s) and the shear viscosity of the cladding material is η _B (Pa · s) at the molding temperature of the sheet-like optical transmission body, the shear rate is The shear viscosity ratio η _A / η _{B in} the region of 20 / s to 10000 / s is expressed by the following formula (4).
_{1.0 <η A / η B ≦} 6.0 (4)
It is preferable to satisfy. Further, the lower limit of η _A / η _B is preferably 1.1, and the upper limit is preferably 4.0. The lower limit of η _A / η _B is significant in that a uniform core layer is formed on the inner side of the two clad layers and the thickness unevenness of the sheet is suppressed. Here, the molding temperature means the temperature of the slit die. Moreover, the range of the shear rate set to 20 / s or more and 10,000 / s or less is based on the shear rate of the resin material existing in the resin flow path formed by the slit die used when shaping the sheet-shaped optical transmission body. It is set based on.

The causes of light leakage from the sheet side surface of the sheet-like optical transmission are due to cracking of the clad (insufficient strength) and the like, optical characteristics of the clad itself, and structural characteristics of the POF (numerical aperture, between core and clad) Structural irregularities, macro bending, micro bending, etc.). In order to prevent such a problem from occurring, the refractive index of the core part measured at 25 ° C. with the sodium D line is n ₁ and the number of layers of the clad part is m. Where n _{2 is} the refractive index of the core portion, n _{3 is} the refractive index of the cladding portion from the core portion to the second layer, and n _{m + 1} is the refractive index of the cladding portion from the core portion to the m-th layer. (5) and (6)
n ₁ > n ₂ > n ₃ >...> n _m > n _{m + 1} (5)
(N ₁ ² −n _{m + 1} ² ) ^1/2 ≧ 0.40 (6)
It is preferable to satisfy.

By satisfying the expression (5), when the sheet-shaped optical transmission is bent, the light leaked from the first cladding can be reflected by the second cladding, and from the side surface when the sheet-shaped optical transmission is bent. Light leakage can be reduced, and use over a long distance is possible. Moreover, by satisfy | filling Formula (6), the bending loss light quantity at the time of bending a sheet-like optical transmission can fully be reduced. In order to set (n ₁ ² −n _{m + 1} ² ) ^1/2 to a value of 0.40 or more, the refractive index n _{m + 1} of the outermost cladding is appropriately set according to the refractive index n ₁ of the core portion. Just choose. For example, when the core portion is polymethyl methacrylate (n ₁ = 1.492) and the cladding portion is a single layer, the refractive index n _{2 of the} cladding is 1.437 or less ((n ₁ ² −n _{m + 1} ² ) ^1/2 is preferably 0.4 or more, more preferably 1.406 or less (0.5 or more), particularly 1.366 or less (0.6 or more). preferable.

  A known material can be used as the material of the core portion of the sheet-like optical transmission body. For example, an organic (co) polymer such as a methyl methacrylate homopolymer (PMMA) or copolymer, a polystyrene resin, a polycarbonate resin, or a cyclic polyolefin resin can be used as a main component. In the case of using a methyl methacrylate copolymer, the content of methyl methacrylate units is preferably 50% by mass or more. Monomers that can be copolymerized with methyl methacrylate include acrylic esters such as methyl acrylate, ethyl acrylate, and n-butyl acrylate, and methacrylate esters such as ethyl methacrylate, propyl methacrylate, and cyclohexyl methacrylate. , Maleimides, acrylic acid, methacrylic acid, maleic anhydride, styrene and the like. Especially, since it is excellent in translucency and durability and it is cheap, it is preferable to comprise the homopolymer of methyl methacrylate as a main component.

  As the resin for forming the first clad layer (the first clad layer), a known material used as a clad material for plastic optical fiber (POF) is used, and the usage environment and purpose of use of the sheet-like optical transmission body. What is necessary is just to select suitably according to etc. Of these, a fluorinated methacrylate polymer and a vinylidene fluoride polymer having a low refractive index and excellent transparency and heat resistance are preferred.

Examples of the fluorinated methacrylate polymer include the following general formula (I):
_{CH 2 = CX-COO (CH} 2) m (CF 2) n Y (I)
(In the formula, X represents a hydrogen atom or a methyl group, Y represents a hydrogen atom or a fluorine atom, m represents 1 or 2, and n represents an integer of 1 to 12.)
And a copolymer comprising 15 to 90% by mass of the unit (A) of fluoroalkyl (meth) acrylate represented by the formula (10) and 10 to 85% by mass of another copolymerizable monomer unit (B). it can.

  Specific examples of the unit (A) of fluoroalkyl (meth) acrylate include (meth) acrylic acid-2,2,2-trifluoroethyl (3FM), (meth) acrylic acid-2,2,3,3- Tetrafluoropropyl (4FM), (meth) acrylic acid-2,2,3,3,3-pentafluoropropyl (5FM), (meth) acrylic acid-2,2,3,4,4,4-hexafluoro Butyl (6FM), (meth) acrylic acid-1H, 1H, 5H-octafluoropentyl (8FM), (meth) acrylic acid-2- (perfluorobutyl) ethyl (9FM), (meth) acrylic acid-2- (Perfluorohexyl) ethyl (13FM), (meth) acrylic acid-1H, 1H, 9H-hexadecafluorononyl (16FM), (meth) acrylic acid-2- (perfluorooctyl) ethyl (17F) ), (Meth) acrylic acid-1H, 1H, 11H- (icosafluoroundecyl) (20FM), (meth) acrylic acid-2- (perfluorodecyl) ethyl (21FM), etc., linear fluorination Mention may be made of (meth) acrylic acid fluorinated esters having an alkyl group in the side chain.

  The unit (B) of the other copolymerizable monomer is not particularly limited. For example, methyl (meth) acrylate units are used to improve transparency, and (meth) acrylic acid alkyl esters such as ethyl (meth) acrylate and butyl (meth) acrylate are used to improve mechanical properties. Units are preferred. From the viewpoint of improving heat resistance, (meth) acrylic acid cyclohexyl, (meth) acrylic acid methyl cyclohexyl, (meth) acrylic acid bornyl, (meth) acrylic acid isobornyl, (meth) acrylic acid adamantyl (meth) ) Acrylic acid cycloalkyl ester units, (meth) acrylic acid phenyl units, (meth) acrylic acid aromatic ester units such as benzyl (meth) acrylate units; (meth) acrylic acid hexafluoroneopentyl units; N-methyl N-substituted maleimide units such as maleimide, N-ethylmaleimide, N-propylmaleimide, N-isopropylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide; α-methylene-γ-butyrolactone, α-methylene-γ-methyl -Γ-butyrolactone, α-methylene-γ γ- dimethyl -γ- butyrolactone, alpha-methylene -γ- ethyl -γ- butyrolactone, units of alpha-methylene -γ- cyclohexyl -γ- butyrolactone of γ- butyrolactone compound; are preferred.

  The vinylidene fluoride polymer is not only excellent in transparency and heat resistance with a low refractive index, but also as a protective layer for the inner cladding layer or core, while maintaining adhesion, vibration applied to the sheet-like optical transmission body It is particularly preferable as a material having a function of relaxing the stress such as external pressure to improve the bending resistance of the sheet-form optical transmission body and improving the solvent resistance and chemical resistance. Copolymerization of vinylidene fluoride (VdF) unit with at least one of tetrafluoroethylene (TFE) unit, hexafluoropropylene (HFP) unit, perfluoro (fluoro) alkyl vinyl ether (FVE) unit and hexafluoroacetone unit. Although a polymer etc. are mentioned, it is not limited to this. As the copolymer component with the VdF unit, the TFE unit, the HFP unit, and the FVE unit are particularly preferable because the copolymer formed using the VdF unit is excellent in transparency and heat resistance as a clad. preferable.

  Specific examples of the vinylidene fluoride polymer include binary copolymers composed of 60 to 90% by mass of VdF units and 10 to 40% by mass of TFE units, 10 to 60% by mass of VdF units and 20 to 70% by mass of TFE units. And ternary copolymer consisting of 5 to 35% by mass of HFP units, ternary copolymer consisting of 5 to 25% by mass of VdF units, 50 to 80% by mass of TFE units and 5 to 25% by mass of FVE units, and VdF units. Examples thereof include a quaternary copolymer composed of 10 to 30% by mass, TFE units 40 to 80% by mass, HFP units 5 to 40% by mass, and FVE units 0.1 to 15% by mass.

The above-mentioned FVE unit is the following general formula (II)
_{CF 2 = CF- (OCF 2 CF} (CF 3)) a O-R f2 (II)
(Wherein R _f2 represents an alkyl group having 1 to 8 carbon atoms, a fluoroalkyl group, an alkoxylalkyl group or a fluoroalkoxylalkyl group, and a is an integer of 0-3.)
It is shown by.

As this FVE unit, the following general formulas (III) to (VI)
_{CF 2 = CFO (CF 2)} n -OCF 3 (III)
(Where n is an integer from 1 to 3)
CF ₂ = CF (OCF ₂ CF (CF ₃ )) _n O (CF ₂ ) _m CF ₃ (IV)
(Where n is an integer from 0 to 3, m is an integer from 0 to 3)
CF ₂ = CFO (CH ₂ ) _n (CF ₂ ) _m CF ₃ (V)
(Where n is an integer from 1 to 3, m is an integer from 0 to 3)
CF ₂ = CFO (CH ₂ ) _n CH ₃ (VI)
(Where n is an integer from 0 to 3)
It is preferable that it is a unit of the compound represented by either.

Among _{them, CF 2 = CFOCF 3, CF} 2 = CFOCF 2 CF 3, CF 2 = CFOCF 2 CF 2 CF 3, CF 2 = CFOCH 2 CF 3, CF 2 = CFOCH 2 CF 2 CF 3, CF 2 = CFOCH 2 CF ₂ CF ₂ CF ₃ , CF ₂ = CFOCH ₃ , CF ₂ = CFOCH ₂ CH ₃ , and CF ₂ = CFOCH ₂ CH ₂ CH ₃ It is preferable from the viewpoint that the cost can be reduced.

  Furthermore, in order for the vinylidene fluoride polymer to have sufficient transparency and heat resistance as a cladding material, the heat of crystal melting in differential scanning calorimetry (DSC) may be in the range of 10 to 80 mJ / mg. Preferably, it is in the range of 20-70 mJ / mg, more preferably in the range of 40-60 mJ / mg.

  This heat of crystal melting is the amount of heat generated due to the thermal melting of the fluorine-containing olefin resin. As the amount of heat increases, the crystallinity of the fluorinated olefin resin increases and the transparency decreases. Conversely, the smaller the amount of heat, the lower the crystallinity and the better the transparency. In other words, the upper limit values of the above ranges for the heat of crystal melting are significant in terms of the transparency of the cladding, the prevention of light scattering in the cladding, the maintenance of a sufficient amount of light, and the maintenance of light transmission performance in a high temperature environment for a long period of time. is there. In addition, the lower limit of each of the above ranges of the heat of crystal melting is suitable for suppressing the elastomeric properties and stickiness of the cladding material itself, molding stability, maintaining optical transmission performance in a high temperature environment for a long period of time, and moderate transparency of the cladding portion. It is significant in that it can be used as a side light leakage type illumination body.

  The sheet-like optical transmission body can be further coated with a protective layer on the outer side of the clad portion in order to improve bending resistance, heat and humidity resistance, chemical resistance, and cut resistance. As this protective layer, it is preferable to use a material having a Shore D hardness (ASTM D2240) of 50 or more. Specific examples of the material for the protective layer include homopolymers or copolymers of methyl methacrylate, polystyrene resins, polycarbonate resins, and the like. In addition, a copolymer containing at least one of a VdF unit and a TFE unit and having a content of 60% by mass or more, specifically, a VdF / TFE copolymer, a VdF / HFA copolymer, a VdF / HFP copolymer. Polymers, VdF / TFE / HFP copolymers, VdF / TFE / HFA copolymers, TFE / HFP copolymers, ethylene / TFE / HFP copolymers and the like can also be mentioned. However, it is not limited to these.

  When molding a plurality of clad layers of the sheet-form optical transmission body, there is no particular limitation on the molding method other than the core part and the innermost clad part. If there is a soluble solvent, the dip coating method may be used. If the cladding material used for the outer layer and the cladding material used for the core material and the inner layer can be molded at the same temperature, they may be co-extruded from a slit die. Alternatively, a sheet-shaped optical transmission body having a core-cladding structure may be once formed in advance, and then the outer cladding layer may be coated on the outer periphery of the sheet-shaped optical transmission body using a coating apparatus using a crosshead die.

In order to give the sheet-like light transmission body appropriate soft flexibility and mechanical strength, and to suppress dimensional deformation when the sheet-like light transmission body is left in a high temperature environment, the sheet-like light transmission body When the yarn diameter before heat treatment is d ₁ and the yarn diameter after heat treatment is d ₂ when left in a thermostat at 150 ° C. for 20 minutes, the following formula (9)
D = (d ₂ / d ₁ ) ² (9)
The draw ratio D calculated from the above is preferably 1.0 to 3.0, and more preferably 1.4 to 2.5. The lower limit value of the stretching ratio D is significant in terms of the mechanical strength of the sheet-form optical transmission body, the storage stability when wound on a bobbin, the fracture resistance when bent, and the like. The upper limit of the draw ratio D is significant in terms of preventing deterioration of optical transmission performance due to heat shrinkage when used near 100 ° C.

  In the sheet-like optical transmission body, a side end face light leakage preventing layer having a refractive index equal to or higher than the refractive index of the core portion may be provided outside the left and right end faces of the sheet-like optical transmission body. When such a light leakage prevention layer is provided, the light propagating in the core portion out of the light propagating in the core part is not reflected at the interface, and is refracted to the outer light leakage prevention layer having a higher refractive index to be contained in the core material. Get out of. Therefore, irregular reflection on the end surface on the core side does not occur, and stabilization of the brightness of the entire sheet is promoted.

  The material used for the light leakage prevention layer on the side end face can be appropriately selected in accordance with the refractive index of the core material, compatibility with the core material, and the like. In particular, in the case of a sheet-like optical transmission body using PMMA as the core material, the material for the end face light leakage prevention layer includes UV curable acrylates such as urethane acrylate and epoxy acrylate, polybenzyl methacrylate, polyphenyl methacrylate, poly Acrylic polymers such as cyclohexyl methacrylate, poly-2-bromoethyl methacrylate, poly-p-bromophenyl methacrylate, poly-α-naphthyl methacrylate, and copolymers thereof, acrylic copolymers such as styrene-methyl methacrylate copolymer Polymers, transparent thermoplastic resins such as polycarbonate, polystyrene, polyacrylonitrile, polycarbonate, and copolymers thereof are preferred. However, the resin material is higher than the refractive index of the material used for the core material and high in transparency, and is not limited to the materials described above, and various materials can be appropriately selected. The method of applying the light leakage prevention layer to the sheet-like optical transmission body is specifically a method of coating an ultraviolet curable resin, a method of coating a thermoplastic resin, or the like, a method of applying the light leakage prevention layer material by dissolving it in a solvent Etc. The method is not particularly limited, and can be appropriately selected according to the material to be used. It is preferable to use a coating method using an ultraviolet curable resin as a method of simply applying the sheet-like transmission body while suppressing excessive heat deterioration and solvent deterioration.

  Further, in the sheet-like optical transmission body, achromatic light shielding layers may be provided on the left and right end faces of the sheet-like optical transmission body. The provision of the achromatic light-shielding layer has an effect of efficiently attenuating light leaked or reflected on the left and right end faces of the sheet-like optical transmission body. Specifically, the achromatic color light-shielding layer may be applied by coating with black paint or by adding a black color to a thermoplastic resin colored in a range of 0.2 to 5% by mass or black. The method of coat | covering ultraviolet curable resin etc. is mentioned. However, it is not limited to these methods. The thickness of the light shielding layer is not particularly limited as long as it has at least a thickness sufficient to provide a light shielding effect.

  Further, instead of the achromatic light shielding layer, a thin film made of a metal or an oxide, nitride or carbide thereof may be formed as the light shielding layer. Specific examples of the metal or oxide, nitride or carbide forming the light shielding layer include gold, silver, copper, aluminum, stainless steel, silicon, tin, magnesium, zinc, lead, chromium, nickel chrome, iron , Indium, tungsten, titanium, titanium nitride, titanium carbide, and alloys thereof, and those containing at least one of aluminum oxide, titanium oxide, silicon oxide, magnesium oxide, and tin oxide as a main component. .

  There is no particular limitation as a method for forming such a light shielding layer made of a metal, an oxide thereof, a nitride or a carbide on both left and right end faces of the sheet-like optical transmission body. For example, known methods such as vacuum plating, electroless plating, and spraying can be used as a method for forming a light-shielding layer without impairing the performance of the sheet-like optical transmission body. The thickness of the layer is preferably in the range of 5 to 1000 nm.

  Next, the manufacturing method of the sheet-form optical transmission body of this invention is demonstrated in detail.

  The method for producing a sheet-shaped optical transmission body according to the present invention includes forming a raw sheet of the sheet-shaped optical transmission body by melt extrusion using a die having slit-shaped discharge ports, and cladding the both ends of the sheet-shaped optical transmission body. The part is cleaved after the sheet is formed.

  The die having the slit-shaped discharge port is not particularly limited. However, after forming a layer structure that covers the periphery of the transparent core material with one or more types of sheath material, it has a widened section where the channel cross-sectional shape gradually deforms toward the slit-like discharge port, and maintains the layer structure In this state, a die having a shape that can be discharged with a predetermined width and thickness is suitable. It is preferable to use such a slit die. As a result, it is possible to perform shaping while controlling the sheet thickness and the clad thickness to be thin and uniform.

  Furthermore, after shaping by melt extrusion using a die, it is preferable to cleave the left and right ends so that the surface roughness Ra is smoothed to 1 μm or less. It is also possible to obtain a plurality of sheet-shaped optical transmission bodies by cleaving from one wide sheet-shaped optical transmission body according to a desired width. A known technique can be used in the surface processing of both end faces. In particular, the method using mirror cutting using a diamond blade and the method of polishing the end face after cleaving are preferable in that the entire left and right end faces can be obtained uniformly and sufficiently smooth.

  Hereinafter, the illuminating device provided with the sheet-like optical transmission body of the present invention will be described in detail.

  An illumination device provided with a sheet-like light transmission body is roughly composed of at least a sheet-like light transmission body and a light source device optically connected to at least one end of the sheet-like light transmission body. For example, it is possible to provide an end face leakage type illumination device in which a light source device is optically connected to one end portion of a sheet-like optical transmission body and light is leaked from one end portion on the opposite side to which the light source device is connected. Alternatively, the light source device can be optically connected to at least one end of the sheet-like light transmission body to provide a side-light leakage type illumination device that leaks light from the side surface portion of the sheet-like light transmission body.

  In the case of the side light leakage type illumination device, in order to leak light from the desired side surface portion of the sheet-like light transmission body to the outside, the surface of the sheet-like light transmission body is subjected to a surface roughening treatment or removal of the clad portion. It is necessary. Specifically, a surface heat treatment method that melts a part of the side surface of the sheet-like light transmission body, a chemical blast method that dissolves the surface of the sheet-like light transmission body by chemical or electrochemical treatment, It is possible to use a shot blasting method in which an abrasive or a similar material is vigorously struck against the surface of the sheet-like optical transmission body.

  As for the surface heat treatment method, a conventional heating and melting method, for example, a method in which only a side surface portion where light leakage of a sheet-like optical transmission body is desired is heated in a heating furnace or is melted by pressing a hot plate. Can do. In this case, since it becomes easy to generate bubbles in the sheet-like optical transmission body during the heat treatment, it is necessary to perform the heat treatment under vacuum conditions.

  Examples of other surface heat processing methods include heat generation cutting methods such as laser cut processing, ultrasonic cutter processing, and hot cutter processing. In the case of these processing methods, for example, laser cutting, there is an advantage that the clad portion can be cut easily and precisely by adjusting the focus and output of the laser according to the material of the sheet-like optical transmission body and the thickness of the sheet.

  For shot blasting, drilling surface with fine powder such as glass, alumina, steel, silica sand, magnetite, and gold sand using abrasives (blasting material) and high pressure water and compressed air from a small nozzle connected to the compressor. A typical example is a sand blasting method in which the surface is polished by spraying. Compared to surface heat treatment and chemical blasting, shot blasting (especially sand blasting) is capable of roughening without damaging the sheet-like optical transmission body composed of organic polymers. Therefore, it is particularly preferable as a method for processing a sheet-like optical transmission body.

  A light source device used for an illumination device is used by being optically connected to an end face of at least one end of a sheet-like optical transmission body. Moreover, the form which connects and uses a light source device to the both ends of a sheet-like optical transmission body may be sufficient.

In the light source device, preferably, the plane located at a distance L ₁ from the light emitting end of the light source is the plane H, the center point of the irradiation spot on the plane H is the point P ₁ , and the center point P ₁ of the irradiation spot on the plane H is When a point where the distance from the point is L ₂ and the luminance is 50% of the luminance at the point P ₁ is a point P ₂ , the following formula (10)
NA = sin {tan ⁻¹ (L ₁ / L ₂ )} Equation (10)
It is preferable to use a light source having an aperture angle NA of 0.15 or more defined by

  If the aperture angle NA is 0.15 or more, a sufficient amount of light can be uniformly supplied to the entire surface of the sheet-like light transmission body connected to the light source device. It is not necessary to install any parts or perform post-processing, which is advantageous in reducing the size and cost of the lighting device, and can maintain the function as a lighting body.

  As the light source device, for example, a metal halide lamp, a xenon lamp, a high-pressure mercury lamp, a light emitting diode (LED), or a semiconductor laser (LD) having particularly high luminance is used. The reflection boundary, lens mounting, lamp shape, power consumption, and the like can be changed as appropriate according to the purpose of use. When the light source is a highly directional semiconductor laser (LD), a lens having an opening angle NA of 0.15 or more may be installed between the sheet-like optical transmission body and the LD. In particular, a light emitting diode (LED) is particularly preferable because the temperature rise around the light source is small even when it is lit for a long time, so that it is possible to prevent thermal deterioration and melting at the incident end of the sheet-like optical transmission body. .

  FIG. 4A is a schematic diagram when one LED is used at one end of the sheet-like optical transmission body, and FIG. 4B is a schematic diagram when two LEDs are used. When the LED 11 is used as the light source, at least one end of the sheet-like optical transmission body 10 may be provided with one LED 11 at both end portions as shown in FIG. In order to reduce the light leakage spots of the sheet-like optical transmission body 10 and increase the amount of light leakage of the sheet-like optical transmission body 10, two LEDs 11 are provided at both end portions of the end as shown in FIG. A method of introducing incident light of the LED 11 into the sheet-type optical transmission body may be used.

  Hereinafter, the present invention will be described by way of examples. Table 1 shows the evaluation results of the cross-sectional shapes and light leakage uniformity of Examples and Comparative Examples using various materials. In addition, about the evaluation method in the Example of this invention, it implemented by the following method.

(Crystal melting heat (ΔH))
A differential scanning calorimeter (DSC) (manufactured by Seiko Instruments Inc., apparatus name DSC-220) was used for the measurement. The sample was heated to 200 ° C. at a rate of temperature increase of 10 ° C./min, held in that state for 5 minutes and melted, and then cooled to 0 ° C. at a rate of temperature decrease of 10 ° C./min. This operation was repeated again, and the heat of crystal melting at this time was determined.

(Refractive index)
A film-shaped test piece having a thickness of 200 μm was formed by a melt press, and the refractive index (n _D 25) of sodium D line at 25 ° C. was measured using an Abbe refractometer.

(Melt flow rate)
The melt flow rate (MFR) was measured according to Japanese Industrial Standard JIS K7210. The amount of polymer (g / 10 minutes) discharged in 10 minutes from a nozzle having a diameter of 2 mm and a length of 8 mm under the conditions of 210 ° C. and a load of 5 kgf (49 N) was measured.

(Shear viscosity η)
Measure shear viscosity at a shear rate of 20 to 10000 (/ s) under conditions of a die diameter of 1 mm, a die total length of 16 mm, and a measurement temperature of 230 ° C. did.

(Stretch rate)
When the sheet-shaped optical transmission body is left in a thermostat at 150 ° C. for 20 minutes, when the yarn diameter before heat treatment is d ₁ and the yarn diameter after heat treatment is d ₂ , (drawing ratio) = (d ₂ / d ₁ ) Calculated from ² .

(Measurement of surface roughness Ra)
The center line average roughness Ra was measured on the left and right side end faces of the sheet-form optical transmission body according to JIS B0601 using a surface roughness measuring machine (manufactured by Kosaka Laboratory, apparatus name Surfcoder SE-30H).

(Sheet thickness)
The average sheet thickness is obtained by measuring the sheet thickness of 15 points in a 1 m sample, and obtaining an average value. The sheet thickness 3s is obtained by multiplying the standard deviation s by three.

(Sheet thickness)
The average clad thickness is obtained by dividing a sample of 1 m into 15 and measuring the clad thickness to obtain an average value. The clad thickness 3s is obtained by multiplying the standard deviation s by three.

(Cross-sectional shape)
The cross-sectional shape is the result of observing the cross-sectional shape visually and with a microscope after the sample was cleaved and the surface was sufficiently polished. The cross-sectional shape was indicated by ◎, ○, Δ, and × in order of more uniform shape.

(Light leakage uniformity)
The light leakage uniformity is a result of visually confirming the light leakage when the light from the LED light source (opening angle = 0.17) is incident from one end face as shown in FIG. In the order of more uniform light leakage, it is indicated by ◎, ○, Δ, ×.

(Sheet flexibility)
Sheet flexibility is the result of confirming how much flexibility is obtained when the sample is bent. If the sample breaks or cannot be folded, it is marked as x, depending on the degree of bending. , ○, △, ×.

Materials of Examples 1 to 13 and Comparative Examples 1 to 8 below, MFR, heat of crystal melting, η _A / η _B , various sheet dimensions, side end surface roughness Ra, cross-sectional shape, light leakage uniformity The evaluation results of sheet flexibility are summarized in Table 1.

(Example 1)
In the apparatus configuration shown in FIG. 5, a sheet was manufactured. As the nozzle 12, a nozzle having a widened portion with a slit-like discharge port width of 40 mm and a thickness of 0.5 mm downstream of the nozzle that joins the core material and the clad material to form a two-layer structure was used. A polishing roll was used as the nip roll 13 (cooling roll), the roll gap was set to 0.4 mm, which was slightly thinner than the discharge port thickness, and cooling was performed by the cooling device 16.

The core material is PMMA (Mitsubishi Rayon Co., Ltd., trade name Acrypet, MFR = 2.4, refractive index 1.492), and the sheath material is VP-50 (Daikin Industries, Ltd., VdF / TFE = 80). / 20 mol%, MFR = 15.2, refractive index 1.402, heat of crystal melting 59 mJ / mg). When the shear viscosity of the core material and the clad material was measured, the shear viscosity ratio η _A / η _B at a shear rate of 20 / s to 10000 / s was 1.02 to 2.42. The operating conditions of the two melt extruders 14 and the metering gear pump 15 for each resin were standard conditions for each resin. The nozzle temperature was 230 ° C., and a sheet-like material 10 ′ having a width of 40.1 mm was produced. The both end portions of the obtained sheet-shaped raw material were mirror-cut with a diamond blade with a width of 50 μm to obtain a sheet-shaped optical transmission body in which both end surfaces were mirror-finished. The obtained sheet-like optical transmission body had a width of 40 mm, a thickness of 0.4 mm, and a clad material thickness of 45 μm, and the sheet thickness and clad thickness maintenance were uniform in any part of the cross section. The stretch ratio of this sheet was measured and found to be 1.1. Further, the surface roughness Ra of the left and right end faces of the sheet-like material was 0.06 μm. After sufficiently polishing the short end face existing in two places of the obtained sheet-like optical transmission body (sheet length 1 m), light from the LED light source (opening angle NA = 0.17) as shown in FIG. ) Was incident, it was a sheet-like optical transmission body in which light leakage from the side surfaces of the sheet-like material and all the left and right side end surfaces was uniform.

(Comparative Example 1)
Except for cutting both side ends of the sheet-like material obtained in Example 1 with a thickness of 48 μm and polishing it with a lapping film having a particle size of 1 μm so that the width of the sheet-like material is 40 mm. A sheet-like optical transmission body was manufactured under the same conditions. The surface roughness Ra of the left and right side end faces of the obtained sheet-like optical transmission body was 1.10 μm.

  After sufficiently polishing the short end face existing in two places of the obtained sheet-like optical transmission body (sheet length 1 m), light from the LED light source (opening angle NA = 0.17) as shown in FIG. ) Was incident, the sheet-like optical transmission body had a non-uniform light-leakage balance in which the light leakage from the left and right end faces was larger than the light leakage from the side surface of the sheet-like material.

(Examples 2-7 and Comparative Examples 2-7)
A sheet-like material was produced under the same conditions as in Example 1 except that the sheet width, sheet thickness, and cladding thickness were changed as shown in Table 1.

  Table 1 shows the results of evaluating various thicknesses, thickness variations s, cross-sectional shapes, light leakage uniformity, and sheet flexibility of the obtained sheet-like optical transmission body. Like Example 2 and Comparative Example 2, Example 3 and Comparative Example 3, the same numbers in Example and Comparative Example were set to be within and outside the range in the vicinity of the range of the present invention.

  As shown in Table 1, when the value of L / d in the sheet-like optical transmission body exceeds the upper and lower limits of the range of the present invention, the cross-sectional shape is good, but the sheet-like material (sheet length 1 m) After sufficiently polishing both short end faces, as shown in FIG. 4 (a), a sheet-like light transmission body having a non-uniform light leakage balance when light from an LED light source is incident (Comparative Examples 2 and 3). When the values of L / d were within the range of the present invention, the sheet-shaped optical transmission body had good cross-sectional shape and uniform light leakage (Examples 2 and 3).

  Further, when the thickness d in the sheet-like optical transmission body exceeds the upper and lower limits of the range of the present invention, the flexibility of the sheet is lowered, and in the case of Comparative Example 4, the sheet breaks when bent, and the comparison In the case of Example 5, it was a sheet-like optical transmission body that was subjected to flexibility. When the thickness d of the sheet-shaped optical transmission body is within the range of the present invention, the sheet-shaped optical transmission body has good flexibility.

  Further, when the thickness b of the clad portion in the sheet-like optical transmission body exceeds the upper and lower limits of the range of the present invention, the cross-sectional shape is good, but both short end faces of the sheet-like object (sheet length 1 m) are sufficient. After polishing, when light from an LED light source is incident from one end face as shown in FIG. 4 (a), light leakage near the light incident portion increases, and sufficient light can be transmitted to the emission side. None (Comparative Examples 6 and 7). When the thickness b of the clad part in the sheet-shaped optical transmission body was within the range of the present invention, the sheet-shaped optical transmission body had good cross-sectional shape and uniform light leakage (Examples 6 and 7).

(Comparative Example 8)
A sheet-like material was produced under the same conditions as in Example 1 except that the clad thickness b in the sheet-like optical transmission body was 195 μm. Table 1 shows the results of various numerical values and cross-sectional shapes, light leakage uniformity, and sheet flexibility. Although the obtained sheet had a good cross-sectional shape, the thickness of the core portion was reduced, and transmission was not possible.

(Example 8)
A sheet-like material was produced under the same conditions as in Example 1 except that PMMA having a large MFR (MFR = 20) was used as the core material. The shear viscosity ratio η _A / η _{B in} the range of 20 / s to 10000 / s was 0.58 to 1.23. The average size of the obtained sheet was 30 mm in width, 0.24 mm in thickness, and the thickness of the clad material was 60 μm. The stretch ratio of this sheet was measured and found to be 1.3. The surface roughness Ra of the left and right end faces of the sheet-like material was 0.06 μm.

  Variations in the thickness of the obtained sheet and the thickness of the clad material were slightly larger than those in Example 1, and in particular, the sheet-shaped optical transmission body had a slightly large thickness variation in the core material in the sheet cross section. After sufficiently polishing both short end surfaces of the sheet (sheet length 1 m), the light from the LED light source was incident from one end surface as shown in FIG. 4 (a). It was a sheet-like optical transmission body that maintained light uniformity.

Example 9
Implementation was performed except that VP-100 (trade name, manufactured by Daikin Industries, Ltd., VdF / TFE = 80/20 mol%, MFR = 45, refractive index 1.402, crystal melting heat 59 mJ / mg) was used for the clad material. A sheet was produced under the same conditions as in Example 1. The shear viscosity ratio η _A / η _{B in} the range of 20 / s to 10000 / s was 2.05 to 4.85. The obtained sheet had a width of 40 mm, a thickness of 0.4 mm, and a thickness of the clad material of 22 μm. The sheet thickness and the clad thickness were uniform in any part of the cross section. The stretch ratio of this sheet was measured and found to be 1.3. Further, the surface roughness Ra of the left and right end faces of the sheet-like material was 0.06 μm.

  After sufficiently polishing both short end faces of the obtained sheet-like material (sheet length 1 m), when light from an LED light source is incident from one end face as shown in FIG. It was a sheet-like optical transmission body in which light leakage from all surfaces was uniform.

Example 10
VP-2000 (trade name, manufactured by Daikin Industries, Ltd., VDF / TFE / HFP = 48/439 (wt%), MFR = 45, refractive index 1.374, heat of crystal melting 14 mJ / mg) is used for the clad material. A sheet-like material was produced under the same conditions as in Example 1 except that. The shear viscosity ratio η _A / η _{B in} the range of 20 / s to 10000 / s was 1.43 to 3.39. The obtained sheet had a width of 26 mm, a thickness of 0.3 mm, and a thickness of the clad material of 32 μm. The sheet thickness and the clad thickness were uniform at any part of the cross section. The stretch ratio of this sheet was measured and found to be 1.3. Further, the surface roughness Ra of the left and right end faces of the sheet-like material was 0.06 μm.

  After both short end faces of the obtained sheet (sheet length 1 m) are sufficiently polished, light from the LED light source is incident from one end as shown in FIG. The sheet-like optical transmission body was uniform in light leakage from all the end faces.

Example 11
Other than using LJ-202042 (trade name, manufactured by Sumitomo 3M Co., Ltd., VDF / TFE / HFP / FVE copolymer, MFR = 21, refractive index 1.350, heat of crystal melting 8 mJ / mg) for the clad material Produced a sheet-like material under the same conditions as in Example 1. The shear viscosity ratio η _A / η _{B in} the range of 20 / s to 10000 / s was 1.71 to 4.04. The obtained sheet had a width of 18 mm, a thickness of 0.35 mm, and a clad material thickness of 20 μm, and the sheet thickness and clad thickness were uniform in any part of the cross section. The stretching ratio of this sheet was measured and found to be 2.0. Further, the surface roughness Ra of the left and right end faces of the sheet-like material was 0.06 μm.

  Although the cross-sectional shape of the obtained sheet and the uniformity of light leakage did not reach the sheet-like optical transmission body obtained in Example 1, it was a sufficiently uniform sheet-like optical transmission body.

(Example 12)
Other than using THV220G (trade name, manufactured by Dyneon, VDF / TFE / HFP = 40/40/20 (wt%), MFR = 12, refractive index 1.364, crystal melting heat 5 mJ / mg or less) as the clad material Produced a sheet-like material under the same conditions as in Example 1. The shear viscosity ratio η _A / η _{B in} the range of 20 / s to 10000 / s was 1.81 to 3.73. The obtained sheet had a width of 40 mm, a thickness of 0.39 mm, and a thickness of the clad material of 41 μm. The sheet thickness and the clad thickness were uniform in any part of the cross section. The stretch ratio of this sheet was measured and found to be 1.3. Further, the surface roughness Ra of the left and right end faces of the sheet-like material was 0.06 μm.

  The clad portion coated on the side surface portion of the obtained sheet-like material was higher in transparency than the sheet-like optical transmission body obtained in Example 1. Further, although the dimensional stability and light leakage uniformity of the obtained sheet-like material were slightly inferior to those of Example 1, it was a sufficiently uniform sheet-like optical transmission body.

(Example 13)
The cladding material is THV610G (trade name, manufactured by Sumitomo 3M Co., Ltd., VDF / TFE / HFP = 20/60/20 (wt%), MFR = 6, refractive index 1.350, crystal melting heat 85 mJ / mg or more). A sheet-like material was produced under the same conditions as in Example 1 except that it was used. The shear viscosity ratio η _A / η _{B in} the range of 20 / s to 10000 / s was 0.91 to 1.87. The obtained sheet had a width of 40 mm, a thickness of 0.28 mm, and a clad material thickness of 49 μm. The stretch ratio of this sheet was measured and found to be 1.3. Further, the surface roughness Ra of the left and right end faces of the sheet-like material was 0.06 μm.

  The clad portion coated on the side surface portion of the obtained sheet-like product was whiter than the sheet-like optical transmission body obtained in Example 1. Further, although the dimensional stability and light leakage uniformity of the obtained sheet-like material were slightly inferior to those of Example 1, it was a sufficiently uniform sheet-like optical transmission body.

  Below, the result of having implemented the light leakage evaluation by the post process of the side end surface with respect to the sheet-like optical transmission body manufactured in Example 1, and the difference in the incident method is shown.

(Example 14)
In the sheet-like optical transmission body (sheet length 1 m) manufactured in Example 1, UV curable resin having a refractive index of 1.5064 was coated on both left and right ends as a side leakage preventing layer. As shown in FIG. 4A, the light from the LED light source was incident on the sheet-like optical transmission body from the one end surface in the same manner as in the first embodiment. This sheet-type optical transmission body was a sheet-shaped optical transmission body in which the entire side surface and side end surface leak evenly before providing the side light leakage prevention layer, but from the side end surface by providing the side light leakage prevention layer, This is a sheet-type optical transmission body in which light leakage is removed, and light leakage occurs only on the side surface.

(Example 15)
In the sheet-like optical transmission body (sheet length 1 m) manufactured in Example 1, a black paint was applied to both left and right ends to provide a light shielding layer. As shown in FIG. 4A, the light from the LED light source was incident on the sheet-like optical transmission body from the one end surface in the same manner as in the first embodiment. This sheet type optical transmission body is a sheet-like optical transmission body in which the entire side surface and side end surface leak light uniformly before the light shielding layer is provided. However, by providing the light shielding layer, light leakage from the side end surface is removed. The sheet-type optical transmission body that leaks light only on the side surface.

(Example 16)
The core portion was exposed by performing a surface roughening treatment using a sandblasting method in a range of about 40 mm in the center of the sheet of the sheet-like optical transmission body (sheet length 1 m) manufactured in Example 1. As shown in FIG. 4 (a), when one LED light source is installed and light is incident on the center part of both side end faces of this sheet-like optical transmission body, the external surface is concentrated from the roughened part. Side light leakage type sheet-like optical transmission body in which light leaks.

(Example 17)
The sheet-shaped optical transmission body (sheet length 1 m) manufactured in Example 1 was subjected to a surface roughening process using the sand blasting method under the same conditions as in Example 7 to expose the core part. As shown in FIG. 4 (b), two LED light sources are installed at both end portions of the end portion of the sheet-like optical transmission body, respectively, and light is incident on the outer surface in a concentrated manner from the roughened portion. Further, the light leakage from the side surface was a sheet-like light transmission body, and the amount of light leakage was larger than that of Example 7.

“PMMA”: Polymethyl methacrylate “VP-50”: manufactured by Daikin Industries, Ltd., VdF / TFE = 80/20 mol%, MFR = 15
“VP-100”: manufactured by Daikin Industries, Ltd., VdF / TFE = 80/20 mol%, MFR = 30
“VP-2000”: manufactured by Daikin Industries, Ltd., VDF / TFE / HFP = 48/43/9 (wt%), MFR = 45
“LJ202042”: VDF / TFE / HFP / FVE copolymer manufactured by Sumitomo 3M Co., MFR = 21
“THV220G”: manufactured by Sumitomo 3M Co., Ltd., VDF / TFE / HFP = 40/40/20 (wt%), MFR = 12
“THV610”: manufactured by Sumitomo 3M Co., Ltd., VDF / TFE / HFP = 20/60/20 (wt%), MFR = 6

  Since the sheet-shaped light transmission body of the present invention has flexibility and flexibility, an illumination device equipped with the sheet-shaped light transmission body is excellent in small size and light weight, irradiation light quantity, uniform light leakage, and manufactured at a lower cost. Is possible. Therefore, it can be used in a wide variety of applications such as sensor applications such as sheet and paper pinhole detection applications, personal computer displays and keyboards, mobile phone screens, liquid crystal panels, and touch control panel backlight applications. The range of use is extremely wide.

It is typical sectional drawing of a sheet-like optical transmission body. It is a graph which shows the range of the sheet thickness and clad thickness of a sheet-like optical transmission body. It is a typical perspective view of a sheet-like optical transmission body. (A) is a schematic diagram in the case of using one LED in the one end part of a sheet-like optical transmission body, (b) is a schematic diagram which shows arrangement | positioning of LED in the case of using two LED. It is a schematic diagram which shows the manufacturing process performed in the Example.

Explanation of symbols

1 Core part 2 Clad part 3 Left and right side end faces (Left and right side end parts)
a core thickness b clad thickness L sheet width d sheet thickness 10 sheet-shaped optical transmission body 10 ′ sheet-shaped optical transmission body 11 LED
12 Nozzle (slit die type)
13 Nip roll 14 Melt extruder 15 Metering gear pump 16 Cooling device

Claims (8)

A side light leakage type illumination device having a sheet-like light transmission body and a light source device optically connected to at least one end of the sheet-like light transmission body,
The sheet-like light transmission body is a flexible and flexible sheet-like light transmission body in which the upper and lower surfaces of a planar core portion made of a transparent organic polymer are covered with at least one clad portion,
The core portion of the sheet-like optical transmission body is composed of a methyl methacrylate homopolymer or copolymer, a polystyrene resin, a polycarbonate resin, or a cyclic polyolefin resin,
The clad portion of the sheet-like optical transmission body is made of a fluorinated methacrylate polymer or a vinylidene fluoride polymer,
When the sheet width of the sheet-like optical transmission body is L (mm) and the sheet thickness is d (mm), the following formula (1)
10 ≦ L / d ≦ 10000, 0.1 ≦ d ≦ 1.0 (1)
When the thickness of the clad part is b (mm), the following formulas (2) and (3)
b ≦ d / 2−0.01 (2)
0.005 ≦ b ≦ 0.1 (3)
The filled, left and right side end faces of the core portion is not covered with the cladding portion, and, Ri surface roughness Ra der less 1μm measured according to JIS B0601 of the left and right side end faces of the sheet-shaped optical transmission medium,
At the molding temperature of the sheet-form optical transmission body, the amount (g) of the polymer discharged in 10 minutes from a nozzle having a diameter of 2 mm and a length of 8 mm under the condition of a load of 5 kgf (49 N) was defined as a melt flow rate (MFR). When the MFR (M ₁ ) of the material of the core part and the MFR (M ₂ ) of the material of the cladding part have a relationship of M ₁ <M ₂ ,
When the shear viscosity of the material of the core portion is η _A (Pa · s) and the shear viscosity of the material of the cladding portion is η _B (Pa · s) at the molding temperature of the sheet-like optical transmission body , the shear rate is 20 The shear viscosity ratio η _A / η _{B in} the region of / s to 10000 / s is represented by the following formula (4)
_{1.0 <η A / η B ≦} 6.0 (4)
The filling,
Cladding portion of the sheet-like light transmission body, side light leakage type crystal melting heat in the differential scanning calorimetry (DSC) and wherein the Ru consists vinylidene fluoride polymer in the range of 10 to 80 mJ / mg Illumination device. The refractive index of the core part of the sheet-like optical transmission body measured at 25 ° C. with sodium D-line is n ₁ , the number of layers of the cladding part is m, and the refractive index of the cladding part from the core part to the first layer is n ₂ , When the refractive index of the cladding portion from the core portion to the second layer is n ₃ and the refractive index of the cladding portion from the core portion to the m-th layer is _{nm + 1} , the following equations (5) and (6)
n ₁ > n ₂ > n ₃ >...> n _m > n _{m + 1} (5)
(N ₁ ² −n _{m + 1} ² ) ^1/2 ≧ 0.40 (6)
The side light leakage type illumination device according to claim 1, wherein: On the outside of the left and right side end faces of the sheet-like optical transmission member, side light leakage type illumination device according to claim 1 or 2 having a side end face light leakage prevention layer having a refractive index equal to or higher than the refractive index of the core portion. The side light leakage type illumination device according to any one of claims 1 to 3 , further comprising: a light shielding layer made of an achromatic resin or a light shielding layer made of a metal or a metal oxide on a side end surface of the sheet-like optical transmission body. It is a method for manufacturing the side light leakage type illumination device according to any one of claims 1 to 4 ,
A sheet-shaped optical transmission material is formed by melt extrusion using a die having slit-shaped discharge ports, and the clad portions at both ends of the sheet-shaped optical transmission material are cleaved after the sheet is formed. Manufacturing the body, and
A method for manufacturing a side-light leakage type illumination device, comprising a step of optically connecting a light source device to at least one end of the sheet-like optical transmission body. When the clad portions on both side ends of the sheet-like optical transmission body are cleaved after sheet forming, cleave so that the surface roughness Ra measured according to JIS B 0601 on both side end surfaces is smoothed to 1 μm or less. The manufacturing method of the side light leakage type illumination device according to claim 5 . The method of manufacturing a side-light-leakage illumination device according to claim 5 or 6 , wherein a specular cutting machine using a diamond blade is used to cleave the clad portions at both ends of the sheet-shaped optical transmission body after forming the sheet. It is part of a roughening of the side surface of the sheet-shaped optical transmission body portion, or according to any one of claims 1 to 4, the cladding portion, characterized in that to light leakage to the outside from the portion removed Side light leakage type illumination device.

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