JP4765504B2 - Optical filter - Google Patents

Description

  The present invention relates to an optical filter that is used in fields such as optical measurement and optical information communication, and cuts transmitted light and reflected light of a specific wavelength by utilizing a light interference phenomenon of a multilayer film of thermoplastic resin. .

  Conventionally, an optical filter that transmits or reflects light of a specific wavelength is called a band-pass filter or the like, and has been used in various optical measurement fields. These utilize the light interference phenomenon of the reflected light from each interface of the laminated multilayer film, and the structure is 10 to 100 dielectric layers of different inorganic compounds on glass as a substrate. The structure was a laminated dielectric multilayer film. However, since these films are formed by resistance heating, EB (Electron Beam) vapor deposition or sputtering, etc., they require a large vacuum facility, and moreover, in order to obtain a multilayer film, It was necessary to obtain a laminated structure by evaporating the target several times. Therefore, it is unsuitable for enlargement and mass production, and has a problem that it is particularly expensive.

  On the other hand, an optical filter in the field of optical information communication is known as a fiber grating. A fiber grating has a function of transmitting and reflecting light of a specific wavelength by forming a periodic structure in which high refractive index layers and low refractive index layers are alternately arranged in the longitudinal direction of the optical fiber, and has a high density wavelength. It is a passive optical element applied to multiplex communication. This is generally produced by irradiating an ultraviolet laser on a mask having irregularities to form a periodic interference pattern on the fiber and changing the refractive index of the light irradiation part of the interference pattern. . (Patent Document 2) This is because the fiber grating is formed by removing the fiber coating, which is troublesome and further requires a process of fixing the fiber to a glass substrate, for example, for the purpose of reinforcing the part. It was. For this reason, there is a problem that the production efficiency is poor, it is not suitable for mass production, and the cost is increased.

Also, in the case of utilizing the optical interference phenomenon for a film having excellent productivity, it is a laminated film having a structure in which two or more kinds of thermoplastic resins are regularly arranged in the thickness direction and comprising 20 layers or more. Thus, a peak having a reflectance of 30% or more with respect to light having a wavelength of 100 to 100,000 nm is observed, and the ratio of the peak half-value width (λw) to the peak wavelength (λt) (λw / λt) is 0.02 ≦ Laminated films with λw / λt ≦ 0.3 have been proposed. However, these have low light blocking properties due to interference reflection due to poor lamination accuracy, and furthermore, there is a problem such as wavelength shift that the light blocking wavelength region changes due to temperature due to poor thermal stability of optical performance, Application to the optical measurement field and the optical communication field was difficult. (Patent Document 3)
JP 2004-317701 A (page 2) JP 2004-198766 A (2nd page) JP 2003-115446 A (2nd term)

  The present invention provides a low-cost optical filter that is excellent in light blocking performance and excellent in thermal stability of optical performance without requiring a complicated manufacturing process in view of the above-described problems of the prior art. This is the issue.

To solve the above problem, the optical films of the present invention, the thermoplastic resin layer B comprising a thermoplastic resin A layer and the copolyester comprising polyethylene terephthalate is laminated 100 layers or more in the thickness direction, layer thickness The unevenness is 20% or less, the maximum transmittance or reflectance at a wavelength of 250 to 2600 nm is 70% or more, and the shift amount of the reflection spectrum or transmission spectrum in an atmosphere of −5 ° C. and 65 ° C. is 10 nm or less. It is characterized by being.

  The optical filter of the present invention relates to a band-pass filter that transmits or reflects light of a specific wavelength, and more specifically, is used in the field of optical measurement or optical information communication, and has excellent light blocking properties and optical characteristics. The present invention provides a low-cost optical filter having excellent thermal stability.

  Details of the present invention will be described below.

It is important that the optical filter of the present invention has a structure in which at least two kinds of thermoplastic resins are alternately laminated in the thickness direction. With such a laminated structure, the reflection wavelength and the reflectance can be controlled. For example, in the case of comprising three types of thermoplastic resins A, B and C, a random layer structure may be used, but from the viewpoint of increasing the reflectance, A (BC) _n A, A (BAC) _n A (n Are preferably laminated in a regular arrangement such as (natural number). Further, from the viewpoint of manufacturing cost and simplicity in optical design, it is preferable to adopt a structure in which two types of thermoplastic resins are alternately laminated like A (BA) _n .

The control of the reflectivity by the laminated structure uses the principle of interference reflection. Interference reflection is a phenomenon in which a large number of thin layers having different media, that is, different refractive indexes are stacked, and reflected lights on the boundary surface interfere with each other and strengthen each other. For example, for a multilayer film in which a large number of two types of thermoplastic resins A and B are alternately stacked, when light is incident perpendicularly to the surface of the film, the wavelength λ (nm) satisfying the following condition is satisfied at the interface of the stack. The light is reflected.
2 · (n _A · d _A + n _B · d _B ) = nλ (1)
here,
n _A : Refractive index of thermoplastic resin A n _B : Refractive index of thermoplastic resin B d _A (nm): Layer thickness of thermoplastic resin A d _B (nm): Layer thickness of thermoplastic resin B n: It is a natural number representing the order of reflection. Accordingly, the reflection wavelength λ can be arbitrarily set by selecting the thermoplastic resins A and B and adjusting the layer thickness.

  The layer thickness of each constituent layer is preferably set according to the refractive index of the thermoplastic resin that constitutes each layer. For example, the refractive index of the thermoplastic resin forming the laminated structure in an example as described later is in the range of about 1.4 to 1.7, and in this case, the thickness of each layer is a viewpoint that makes it easy to use optical interference. To a value in the range of 30 to 650 nm. More preferably, it is 50-350 nm.

  The laminated structure of the optical filter of the present invention is determined according to the target filter performance. For example, a narrow-band reflection filter having a function of reflecting only light of a specific wavelength and transmitting other light forms a periodic structure in which the thickness of the resin A and the thickness of the resin B are constant in the thickness direction. An edge filter that has a function to transmit or reflect all light having a wavelength longer than or equal to a certain wavelength needs to form an inclined structure in which the layer thickness of the resin A and the layer thickness of the resin B change at a certain rate. There is. In addition, in any filter such as a narrow band transmission filter, a wide band transmission filter, a polarization beam splitter, etc., if the target function is determined, the optimum structure can be determined by optical calculation. For the theory of optical calculation, see H.H. A. McLeod (translated by Shigetaro Ogura) “Optical Thin Film” (Nikkan Kogyo Shimbun) (1989), Mitsunobu Koisoyama “Basic Theory of Optical Thin Film” (Opttronics) (2003).

  From the viewpoint of achieving high light reflection performance, the number of laminated optical filters of the present invention needs to be 100 or more, preferably 200 or more, and more preferably 400 or more.

The laminated structure and the number of laminated layers in the present invention are adjusted by the structure of the slit portion of the feed block that plays the role of joining and laminating the thermoplastic resins A and B.
FIG. 1 shows a top view of a feed block for joining and laminating resins. FIG. 2 shows a side view of the slit plate 3, the short tube 8, the base 9, and the cast drum 10 of the feed block. FIG. 3 shows a front view of the feed block 5, the short tube 8, the base 9, and the cast drum 10.

  Hereinafter, this will be described in detail. Polymers A: 1 and B: 2 supplied from the respective extruders are filled into the manifold 4 in the feed block, respectively, and then the polymer A: 1 and the polymer B: 2 are fed into the slit plate 3 which is a polymer junction. By alternately flowing in, a laminated structure is achieved. However, the polymer A flows into only the slit portion 6 in the slit plate 3 from the front side of the paper surface, while the polymer B flows into only the slit portion 7 from the back surface of the paper surface, so that a multi-layer flow is formed immediately before the short pipe. Merge to obtain a laminated structure. A desired laminated structure is designed by adjusting the number of laminations and adjusting the number of slit portions and the thickness of each slit portion by adjusting the gap and length of the slit portions. Next, the laminated polymer stream is cooled and solidified on the casting drum through the short tube 8 and the base 9 to become a sheet having a laminated structure.

As an aspect of a preferable laminated structure of the optical filter according to the present invention, for example, an edge filter will be described. First, the wavelengths λ and λ ′ that are the ends of the desired reflection wavelength band are determined, and the layer thicknesses d _A and d _B corresponding to the reflection wavelength λ according to the above formula (1) from the known ejection ratio and refractive index, Further, the layer thicknesses d _A ′ and d _B ′ corresponding to the reflection wavelength λ ′ are obtained. The layer thickness between d _A → d _A ′ and between d _B → d _B ′ is a laminated structure in which the layer thickness distribution changes continuously with monotonous increase or monotonic decrease, respectively. It is preferable that the gradient structure of the layer thickness in the thickness direction adopts a relationship of an equidistant sequence and a geometric sequence. Moreover, it is preferable that the inclination degree which is a ratio of the maximum thickness layer with respect to the minimum thickness layer of the thermoplastic resin A is 0.5 or more from a viewpoint of achieving high reflective performance. More preferably, it is 0.7 or more.

As the thermoplastic resin forming the laminated structure of the optical filter according to the present invention, polyester is particularly preferable from the viewpoint of heat resistance, dimensional stability, and cost. These may be homopolymers or copolymerized polymers.

  The polyester is obtained by polymerization from a monomer mainly composed of an aromatic dicarboxylic acid or aliphatic dicarboxylic acid and a diol.

  Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4′-diphenyldicarboxylic acid, 4,4'-diphenyl ether dicarboxylic acid, 4,4'-diphenylsulfone dicarboxylic acid and the like can be mentioned. Examples of the aliphatic dicarboxylic acid include adipic acid, suberic acid, sebacic acid, dodecanedioic acid and the like. Of these, terephthalic acid and 2,6-naphthalenedicarboxylic acid are preferred. Only one acid component may be used alone, or two or more acid components may be used in combination. Furthermore, oxyacids such as hydroxybenzoic acid may be partially copolymerized.

  Examples of the diol component include ethylene glycol, 1,2-propanediol, 1,3-propanediol, neopentyl glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, diethylene glycol, triethylene glycol, polyalkylene glycol, 2,2-bis (4-hydroxy And ethoxyphenyl) propane. Among these, ethylene glycol can be preferably used. A diol component may be used individually by 1 type and may use 2 or more types together.

  In particular, polyesters include polyethylene terephthalate and its polymer, polyethylene naphthalate and its copolymer, polybutylene terephthalate and its copolymer, polybutylene naphthalate and its copolymer, and polyhexamethylene terephthalate and its copolymer. Examples thereof include a polymer, polyhexamethylene naphthalate and a copolymer thereof, and polyethylene terephthalate and a copolymer thereof are particularly preferable.

Further, as a combination of at least two kinds of thermoplastic resins, from the viewpoint of achieving high reflectance, a polyester obtained by copolymerizing a layer comprising polyethylene terephthalate and cyclohexanedimethanol, adipic acid, sebacic acid, isophthalic acid, and the like Ru is composed of a a comprising at layer. The amount of copolymerization is preferably 5 to 50 mol% in the case of adipic acid, sebacic acid, isophthalic acid and the like, and in particular, from the viewpoint of excellent thermal stability of optical performance, use a polyester copolymerized with cyclohexanedimethanol. Is most preferred. In that case, an ethylene terephthalate polycondensate having a copolymerization amount of cyclohexanedimethanol of 15 to 40 mol% is most preferable.

  In the optical filter of the present invention, the maximum value of transmittance or reflectance at a wavelength of 250 to 2600 nm needs to be 70% or more. When the reflectance is less than 70%, the performance as a filter is not satisfied, and therefore it is preferably 90% or more, and more preferably 110% or more. When the transmittance is less than 70%, loss such as light absorption is large, so that the performance as a filter is not satisfied. More preferably, it is 80% or more, More preferably, it is 90% or more. When used in the information communication field, the preferred wavelength range is preferably a wavelength range of 600 nm to 1700 nm from the viewpoint of the oscillation wavelength of LEDs, semiconductor lasers, and solid-state lasers.

  Further, as the means for achieving the above, by selecting the thermoplastic resin as described above, and further by setting the in-plane refractive index difference between the thermoplastic resins A and B to 0.05 or more, more preferably 0.08 or more. is there. The in-plane refractive index is MD (single film film made of any one of thermoplastic resins A and B formed under the same film forming conditions as an optical filter obtained by alternately laminating thermoplastic resins A and B. It means the average value of the refractive index in the direction of Machine Direction and the refractive index in the direction of TD (Transverse Direction).

  The in-plane refractive index difference is a difference between the in-plane refractive index of the thermoplastic resin A and the in-plane refractive index of the thermoplastic resin B. The in-plane refractive index can be measured using a known abbe refractometer. For example, in the case of a polyethylene terephthalate film oriented and crystallized by known biaxial stretching and heat treatment, the in-plane refractive index is about 1.6 to 1.66. In addition, the copolymerized polyethylene terephthalate that has been stretched and heat-treated under the same conditions is usually melted at a heat treatment temperature of polyethylene terephthalate because the copolymerized polyethylene terephthalate has a melting point or higher, and orientation relaxation occurs. The rate approaches the unstretched state and is about 1.55 to 1.59.

  Furthermore, as a method of achieving a high reflectance, it is necessary to realize a laminated structure in which the layer thickness unevenness is ± 20% or less. When the layer thickness unevenness exceeds ± 20%, the light interference phenomenon hardly occurs, and the light reflection (blocking) performance is deteriorated. Therefore, it is more preferably ± 10% or less. The layer thickness unevenness here is, for example, that the pattern of the lamination forms a periodic structure, and in the thickness direction cross section of the film, the maximum and minimum values of the layer thickness of the same kind of thermoplastic resin obtained from the TEM cross-sectional photograph The difference is divided by the average layer thickness and multiplied by 100. In the optical filter having an inclined structure, a straight line obtained by linear approximation of the graph plot of the relationship between the layer number and the layer thickness obtained from the TEM cross-sectional photograph by the least square method is used as the reference for the average inclined layer thickness distribution. Next, the difference between the layer thickness for each layer number and the reference value is divided by the reference value and multiplied by 100 to obtain the uneven thickness of the inclined layer for each layer number. Further, among these values, the maximum value is the layer thickness unevenness. However, since the surface layer portion is likely to cause stacking disorder, the surface layer portion 20 layers are excluded from the evaluation.

As a means of adjusting the layer thickness unevenness, an optimal combination of thermoplastic resins with good compatibility and similar rheological properties, and in terms of manufacturing equipment, the shape of the slit, which is the polymer confluence, and the polymer flow in the short tube It is important to optimize the shape of the road. For example, the viscosities of the two types of thermoplastic resins A and B used in the laminated structure are both within the range of a shear rate of 125 ± 10 (1 / S) and 4000 poise or less under the extrusion temperature conditions during film formation. And it is preferable that the resin viscosity difference of A and B is 1700 poise or less. Further, from the viewpoint of reducing the stacking disorder at the polymer joining portion, it is preferable to install a gear pump 12 between the filter pack 11 and the feed block 13 to reduce the pulsation of the polymer flow as shown in FIG. The filter may be of the screen changer type, but is preferably a filter pack type in which leaf disk filters are laid down from the viewpoint of filtration accuracy for removing foreign matters such as oligomers and prevention of disorder of lamination. The leaf disk type includes FSS (Fiber Sintered Stereo) obtained by sintering and compressing SUS fibers and PSS (Porous Sintered Stereo) obtained by sintering SUS powder, and FSS having a high foreign matter cutting ability is preferable. Furthermore, the outermost polymer fluid flowing along the wall surface of the polymer tube has an effect of preventing the laminated state from being disturbed as the layer thickness increases. Therefore, as an achievement means, in the thickness direction of the film after casting, the design of the slit portion of the feed block 13 so that the thickness of the outermost layer is 10 times or more that of the inner layer, and / or It is preferable to use pinol 14 which is a polymer merge part. Further, from the viewpoint of not deteriorating the layer thickness unevenness in the polymer tube, the cross-sectional shape of the polymer flow path from the feed block 13 to the die 15 is preferably a square shape. The rectangular aspect ratio (length in the width direction / length in the thickness direction) is preferably 1 or more and 3 or less. Furthermore, the area of the cross-sectional shape should be as wide as possible from the viewpoint of adjusting the flow rate of the polymer and controlling the stacking disorder. Specifically, the cross-sectional areas are alternately stacked so as to pass through the cross-sectional area within a unit time. The discharge amount of the resin is preferably 40 kg / hr / cm ² or less. More preferably, it is 30 kg / hr / cm ² or less, and further preferably 20 kg / hr / cm ² or less.

The shift amount of the reflection spectrum or transmission spectrum in the atmosphere of −5 ° C. and 65 ° C. of the optical filter of the present invention is required to be 10 nm or less. The shift amount of the reflection spectrum or transmission spectrum means the shift amount of the reflection (or transmission) wavelength of the maximum reflectance in the reflection (or transmission) spectrum. When the shift amount exceeds 10 nm, the filter performance is lowered depending on the use environment. Therefore, it is preferably 6 nm or less, more preferably 4 nm or less. The achievement method is achieved by selecting a thermoplastic resin with excellent thermal dimensional stability, and adjusting the film forming conditions, such as the draw ratio, draw temperature, and heat treatment conditions (temperature and TD relaxation rate). can do. In particular, it is important that the solution viscosity of the thermoplastic resin used from the viewpoint of imparting the thermal stability of the optical performance is low, and in the present invention, it is a layer that is difficult to impart oriented crystallization on the manufacturing process conditions. It is important that the solution viscosity of the copolymerized polyethylene terephthalate layer is low. Specifically, the intrinsic viscosity (IV: Intrinsic Viscosity) measured in orthochlorophenol is 0.64 or less . More preferably, it is 0.62 or less. More preferably, it is 0.57 or less. In addition, it is achieved by laminating a material having better thermal dimensional stability than the optical filter of the present invention on the outermost surface of the optical filter or by dispersing it as an additive in a matrix of a thermoplastic resin constituting the optical filter. be able to. For example, it is preferable to use a transparent inorganic material or a high heat-resistant resin as will be described later as an additive or laminated. Examples of the high heat-resistant resin include polyimide, modified polyphenylene ether, polysulfone, polyarylate, polyphenylene sulfide, paraxylene, polyamideimide, polyethersulfone, polyetheretherketone, polyetherimide, epoxy resin, and phenol resin.

  In the optical filter of the present invention, the maximum value of light loss at a wavelength of 250 to 2600 nm is preferably 6 dB or more when light is incident from the direction perpendicular to the plane. When the maximum value is less than 6 dB, when used in the optical information communication field, light having a wavelength to be blocked is transmitted, so that the performance as a filter is not satisfied. Therefore, it is preferably 11 dB or more, more preferably 15 dB or more. As an achievement method, the number of stacked layers needs to be 100 or more. When the number of stacked layers is less than 100, the light interference phenomenon is weak, so that the light reflection (blocking) performance is deteriorated. Therefore, more preferably, it is 200 or more. More preferably, it is 400 or more. Specifically, the means for increasing the number of layers can be achieved by increasing the number of slits in the feed block. In addition, what is used for a light source may be anything as long as it is a publicly known thing, such as a light emitting diode, a semiconductor, a He-Ne laser, and a lamp light source. For a laser having a strong light output, the light source output may be adjusted using an attenuator or the like in some cases.

  The unevenness of the central reflection wavelength of the optical filter of the present invention is preferably 10% or less. If the center reflection wavelength unevenness exceeds 10%, the light reflection (cutoff) wavelength of the optical filter of the present invention varies depending on the use position of the sample, which causes a problem in quality. Therefore, it is preferably 8% or less, more preferably 5% or less. The central reflection wavelength here is the wavelength at the midpoint between wavelengths 1 and 2, which are two intersections where the half of the maximum reflectance and the reflection spectrum or the half of the minimum transmittance and the transmission spectrum intersect. It is. With respect to the central reflection wavelength, a spectroscope is used to collect reflection spectrum data for about 240 seconds at a sampling rate of 1 sec (seconds) in the MD direction of the film at a traveling speed of 50 cm / min. With respect to the reflection spectrum data obtained at a wavelength of 0.3 nm obtained every 1 sec, the wavelength region that becomes noise is deleted, and then, in order to smooth the spectrum, all are thinned out every three steps, and the three-point moving average processing is performed. And ask. A value obtained by dividing the difference between the maximum value and the minimum value at the 240 center reflection wavelengths obtained by the average center wavelength is defined as the center reflection wavelength unevenness (%).

  As a method for achieving the value of the center reflection wavelength unevenness, the thickness unevenness is preferably 8% or less, and more preferably 4% or less. Specifically, this can be achieved by adjusting the draft ratio, stretching temperature, and stretching ratio, which are control parameters on film formation. The draft ratio is a value obtained by dividing the lip gap of the die by the sheet thickness at the time of casting, and is preferably 20 or less. More preferably, it is 10 or less.

In the optical filter of the present invention, at least one inorganic material layer having a thickness of 500 nm or less is preferably laminated. When one or more inorganic material layers having a thickness of 500 nm or less are laminated on a laminated structure made of a thermoplastic resin, heat resistance and weather resistance, which are weak points of the thermoplastic resin, are improved. Further, when the number of the inorganic material layers is two or more and the layer thickness is 50 to 250 nm, a light interference phenomenon occurs in the same manner as the thermoplastic resin layer, so that the filter performance can be supplemented. Therefore, more preferably, there are two or more inorganic material layers having a thickness of 250 nm or less. The inorganic material layer here may be an inorganic compound containing any metal element described in the periodic table, but from the viewpoint of being preferable as an optical filter, SiO ₂ , TiO ₂ , Ti ₃ O ₅ , ZnO, Nb ₂ O ₅ , Ta ₂ O ₅ , ITO, BK7, Al ₂ O ₃ , ZrO ₂ , HfO ₂ , ZnO ₂ , SnO ₂ , ZnS, CeF ₃ , MgF ₂ , other 3d, 4d transition metal oxides and the like are preferable. In addition, examples of the method for forming the layer include vapor deposition methods such as electron beam, heating resistance, sputtering, and ion beam sputtering in an atmosphere having a degree of vacuum of 10 ⁻⁵ torr or less. A beam / heating resistance type vapor deposition method is preferred, and sputter vapor deposition is preferred for the adhesion surface to the film. In addition, when an inorganic compound such as an oxide is formed in a film forming apparatus, it is preferable to use an IAD (Ion-beam Assisted Deposition) method. The IAD method is a process of adding certain accelerated ions from an ion source to a basic vapor deposition method. As other methods, inorganic particles having a particle size of 500 nm or less are dispersed in a binder-containing solution to prepare a coating solution, and this can be performed, for example, by reverse coating, gravure coating, rod coating, or barcode method. Alternatively, a method of applying on an optical filter made of a thermoplastic resin by using a Meyer barcode method, a die coating method, a spray coating method, a spin coating method, or the like may be employed. Examples of the binder include acrylic, polyester, and urethane resin. Examples of the acrylic resin include copolymers selected from methyl methacrylate, ethyl acrylate, n-butyl acrylate, 2-hydroxyethyl acrylate, acrylamide, N-methylol acrylamide, and acrylic acid. The urethane resin is not particularly limited as long as it is a water-soluble or water-dispersible urethane resin having an anionic group, and the main component is obtained by copolymerizing a polyol compound and a polyisocyanate compound. is there. Specifically, a urethane resin whose affinity for water is increased by introducing a carboxylate group, a sulfonate group, or a sulfuric acid half ester base can be used. Examples of polyester resins include terephthalic acid, isophthalic acid, sebacic acid, 5-sodium sulfoisophthalic acid as an acid component, and a copolymer selected from ethylene glycol, diethylene glycol, 1,4-butanediol, and neopentyl glycol as a glycol component. Can be mentioned. Examples of the dispersion include known solvents such as water, ethyl acetate, methyl ethyl ketone, toluene, ethanol, and acetone, and water is preferable from the viewpoint of the environment.

  The optical filter of the present invention preferably contains a pigment in at least one thermoplastic resin layer. The optical filter of the present invention generally uses a light interference phenomenon caused by a multilayer film using a thermoplastic resin that hardly absorbs light from the near ultraviolet to the near infrared, so that light can be controlled only by transmission or reflection. . Therefore, it is easy to obtain the desired spectral characteristics of the optical filter by adding a dye that can selectively absorb light of a specific wavelength. For example, when the wavelength range of the high reflectance obtained by the optical interference phenomenon and the absorption wavelength range of the dye are superimposed, further light blocking performance, and the high reflectance band obtained by the optical interference phenomenon and the absorption wavelength of the dye When the band is continuous, an edge filter that exhibits a wide light blocking band is obtained. Therefore, in the optical filter of the present invention, it is possible to match the transmission and cutoff wavelength ranges to a desired design by utilizing the light blocking performance due to the light interference phenomenon and the light absorption characteristics.

  The pigments here can be classified into pigments (organic / inorganic) and dyes. A pigment is preferable in terms of heat resistance, and an organic pigment is particularly preferable from the viewpoint of affinity with a thermoplastic resin. Organic pigments are roughly classified into azo pigments, phthalocyanine pigments, dyed lakes, heterocyclic pigments, and the like.

  Azo pigments are classified into insoluble azo pigments, azo lake pigments, condensed azo pigments, and metal complex azo pigments. Further, insoluble azo pigments are classified into β-naphthol-based, naphthol-AS-based, acetoacetate arylamide-based insoluble monoazo pigments, acetoacetate arylamide-based, and pyrazolone-based insoluble disazo pigments. Azo lake pigments are classified into β-naphthol type and β-oxynaphthoic acid type.

  The phthalocyanine pigment is classified into copper phthalocyanine, halogenated copper phthalocyanine, metal-free phthalocyanine, and copper phthalocyanine lake.

  Heterocyclic pigments are classified into anthoraquinone pigments, thioindigo pigments, perinone pigments, perylene pigments, quinacridone pigments, dioxazine pigments, isoindolinone pigments, quinofmeron pigments, and isoindoline pigments.

  Other examples include nitrone pigments, alizarin lakes, metal complex azomethine pigments, aniline black, alkali blue, and natural organic pigments.

As described above, an optical filter can be designed by utilizing the absorption wavelengths of these various pigments.
There are two methods for imparting selective wavelength absorptivity to an optical filter: a method of kneading a pigment in a thermoplastic resin in advance, and a method of dissolving the pigment in a solvent and applying it onto the optical filter. In the former method, it is preferable to prepare a master chip in which the pigment concentration with respect to the thermoplastic resin is adjusted to about 1 to 10% by weight, and further dilute the master chip to a desired concentration. Finally, the pigment concentration relative to the thermoplastic resin is preferably 2% by weight or less. More preferably, it is 1% by weight or less. The production method of the master chip can be achieved by a known twin-screw kneading extruder. Further, the latter method can be achieved by the same method as the above-described inorganic compound coating method. However, since the absorption wavelength is shifted due to the compatibility with the pigment, it is preferable to select a solvent having a desired absorption wavelength. For example, water, ethyl acetate, methyl ethyl ketone, toluene, acetone, ethanol and the like can be mentioned, and water is preferable from the environmental viewpoint.

  In addition, the pigment | dye here does not necessarily have an absorption wavelength especially in a visible light region. The absorption wavelength may be in the near infrared to infrared region. For example, dyes having light absorption in the near infrared to infrared region include phthalocyanine dyes, quartalimides, diimonium compounds, perylene pigments in organic systems, and generally ATO (antimony tin oxide), ITO in inorganic systems. (Indium tin oxide), lanthanum-based metal oxides, and the like. In particular, in an inorganic system, the average particle diameter is preferably 100 nm or less, more preferably 50 nm, from the viewpoint of suppressing light scattering due to a difference in refractive index. More preferably, it is 20 nm or less.

In the optical filter of the present invention, it is preferable that the optical filter does not melt even when irradiated with light of 30 dBm. That is, the light resistance is preferably 30 dBm / cm ² or more. Here, the power resistance means the output energy of light up to the extent that the irradiated portion is not melted and deformed when the 1 cm ² region of the optical filter is irradiated with light. When the power resistance is less than 30 dBm, the filter performance deteriorates with time when continuously used. Therefore, it is preferably 30 dBm, more preferably 33 dBm. The dBm is a value measured at 0 dB (reference) when 1 mV of power is consumed, and unit conversion follows the following equation (2).

dBm = 10 × log10 (mW) (2)
As the achievement method, it is achieved that the light absorption rate of each thermoplastic resin constituting the laminated structure is 10% or less in the entire wavelength region of 650 nm to 1600 nm. When light of this wavelength is absorbed by the polymer, it undergoes heat conversion, causing the polymer to melt and deteriorate. Therefore, it is more preferably 5% or less. The light absorption rate can be obtained by subtracting the transmittance and the reflectance from 100. It can also be achieved by adjusting the thickness and density of the optical filter.

  The optical filter of the present invention is preferably stretched in at least one direction. When stretching is applied, physical properties such as thermal dimensional stability and thermomechanical properties are improved, and productivity is improved. In particular, in the case of imparting stretching in only one direction, strong anisotropy appears, which is suitable for applications that require polarization characteristics. That is, the performance of the optical filter changes depending on the polarization direction. Stretching is achieved by stretching between rolls using a longitudinal stretching machine and a stretching method using a tenter method which is a transverse stretching machine. As a method of stretching in two directions, known sequential biaxial stretching, simultaneous biaxial stretching, or the like may be used.

  In the refractive index ellipsoid of at least one thermoplastic resin layer constituting the optical filter of the present invention, the difference between the in-plane refractive index and the in-plane refractive index is preferably 0.04 or less. In the present invention, the refractive index ellipse of a thermoplastic resin layer such as an amorphous resin to which oriented crystallization is hardly imparted in the film production process, or a copolymerized polyethylene terephthalate having a melting point equal to or lower than the heat treatment temperature during film formation. Think about your body. This is because the difference between the in-plane refractive index and the in-plane refractive index is usually 0.04 or more in the thermoplastic resin layer on the side to which oriented crystallization is imparted. Since the thermoplastic resin layer of the present invention is a layer at the nm level, the refractive index cannot be determined directly. Therefore, the refractive index ellipsoid 3 is measured by measuring the refractive index in the triaxial direction of the film when a single film made of only one thermoplastic resin is formed under the same film forming conditions as the optical filter. Find the refractive index of the shaft. That is, by obtaining the maximum and minimum values of the refractive index in the film plane and the refractive index in the film thickness direction, the three-axis refractive index of the refractive index ellipsoid can be obtained. From the obtained three refractive indexes, the difference between the in-plane refractive index and the in-plane refractive index is defined as Δn. However, the in-plane refractive index is an average value of MD and TD or maximum and minimum refractive indexes. If Δn is 0.04 or more, the reflection (blocking) performance decreases depending on the incident angle of light, which is not preferable. Therefore, it is preferably 0.03 or less, more preferably 0.02 or less. As a method to achieve, it can achieve by adjusting the heat processing temperature at the time of film forming, or the copolymerization amount of copolymerized polyethylene terephthalate. The copolymerization amount is preferably 15 mol% or more, and more preferably 30 mol% or more. However, this is not the case when the optical filter is an unstretched film.

  The optical filter of the present invention can be used for various uses as a commercially available hot mirror, cold mirror, half mirror, laser mirror, dichroic filter, heat ray reflective film, near infrared cut filter, monochromatic filter, and the like. For example, displays, optical sensors (optical measuring devices), solar cell reflecting members, anti-counterfeiting, decorative materials, and optical information communication fields. In particular, the optical filter of the present invention is preferably a passive optical element for optical information communication. In other words, in recent years, erbium-doped fiber amplifiers (EDFAs), which are key technologies that make up a wavelength division multiplexing (WDM) communication network that is required to increase capacity and speed, and wavelength division multiplexing. A gain equalizing filter (GFF: Gain Flattening Filter), a narrow band transmission filter (NBPF: NarrowB, etc.), and the like such as a waver (WDM: Wavelength Division Multiplexer) and OADM (Optical Add / Drop Module). is there. GFF flattens the gain wavelength characteristic of EDFA, and NBPF extracts light as signal light by transmitting only light in the target wavelength band, and reflects (blocks: blocks) other light. It has a filter characteristic.

  Specific embodiments for achieving the optical filter of the present invention will be described below.

  For example, in the case of a multilayer film of (AB) n · A, the method for producing a multilayer laminated reflective film of the present invention is from two units of an extruder A corresponding to the A layer and an extruder B corresponding to the B layer. The polymer from each flow path passes through a filter, a gear pump that adjusts the discharge ratio, and a molten product laminated through a multi-manifold die, feed block, square mixer, static mixer, etc. Is obtained by a method of melt-extrusion into a sheet shape using, and then cooling and solidifying on a casting drum to obtain an unstretched film. The square mixer is equipped with a merge section where the polymer that has passed through the channel having a rectangular cross-section is divided into two rectangular channels, and the branched polymers are combined so that they are stacked one above the other. It is the well-known cylinder. By repeating this step, it is possible to obtain a multi-layered laminate. For example, a laminate of two layers of A / B / A3 layers becomes a five-layer laminate when branching / merging once. (In this case, the stack of the A layers is regarded as one layer.) In such a case, the number of stacks can be expressed by (the initial number of layers−1) × 2 to the nth power + 1. However, n means repeating one branching / merging n times. For example, when a 201-layer laminated film is passed twice (also referred to as two steps) through a square mixer, a laminated body of 801 layers is obtained. In addition, since the distribution ratio of the square mixer is usually branched by equal distribution in a flow path having an equal cross-sectional area of 1: 1, the same laminated structure is periodically formed. If the structure of the initial laminated body is an inclined structure, the polymer laminated body after passing through the square mixer can maintain a continuous inclined structure by making the distribution ratio non-uniformly distributed. The initial inclined structure is achieved by adjusting the gap and length of the slit inside the feed block. In addition, it is also preferable from the viewpoint of not disturbing the internal laminated state that the resin supplied from the extruder C is joined to the outermost layer of these laminated structures using pinol to form a cover layer. Further, by adding particles only to the outermost layer supplied from the extruder C, it is possible to impart easy slipping without reducing the reflection performance. In addition, as a means for not disturbing the internal lamination, a method of designing a wide slit width in the feed block corresponding to the outermost layer may be mentioned.

  In particular, as a laminating apparatus used in the present invention, it is preferable to use only a feed block without using a square mixer from the viewpoint of increasing the laminating accuracy in the thickness direction. The lamination ratio (A / B) between the thermoplastic resins A and B is preferably 0.5 to 3 from the viewpoint of increasing the reflectance. More preferably, it is 0.9-1.7. The lamination ratio corresponds to the discharge ratio of the thermoplastic resin A and the thermoplastic resin B from the extruder. More preferably, the unstretched film can also be obtained by a method of stretching at a temperature equal to or higher than the glass transition point (Tg) of the resin composition. The stretching method at this time is preferably stretched in at least one direction from the viewpoint of thermal dimensional stability. In particular, biaxial stretching is preferably performed by a known biaxial stretching method. The known biaxial stretching method may be a method of stretching in the width direction after stretching in the longitudinal direction, a method of stretching in the longitudinal direction after stretching in the width direction, and a plurality of stretching in the longitudinal direction and stretching in the width direction. You may carry out in combination. For example, in the case of a stretched film composed of polyester, the stretching temperature and the stretching ratio may be any amount, but in the case of a normal polyester film, the stretching temperature is 80 ° C. or more and 130 ° C. or less, and the stretching ratio is 2 times. It is preferably 7 times or more. More preferably, the stretching temperature is 90 ° C. or more and less than 110 ° C., and the stretching ratio is 3.4 times or more and 5 times or less from the viewpoint of reducing the thickness unevenness. The stretched film is then heat treated. This heat treatment is generally performed at a temperature higher than the stretching temperature and lower than the melting point. In the case of ordinary polyester, it is preferably performed in the range of 130 ° C. to 250 ° C., but more preferably in the range of 200 ° C. to 240 ° C. from the viewpoint of suppressing the heat shrinkage rate. Furthermore, in order to provide the thermal dimensional stability of the film, it is preferable to perform a relaxation heat treatment of about 2 to 10% at a temperature not lower than the glass transition temperature of the film and lower than 200 ° C. The thickness of the optical filter of the present invention is determined from the balance between the thickness of each layer and the total number of layers, and is usually preferably 5 μm to 200 μm. Further, in the optical filter of the present invention, various additives such as antioxidants, heat stabilizers, lubricants, pigments, dyes, antistatic agents, fillers, nucleating agents, etc., do not deteriorate their properties. It may be added to. In particular, it is preferable to add an easy lubricant from the viewpoint of imparting slipperiness. As an easy lubricant, it can divide roughly into an organic and inorganic lubricant. As the shape, shape particles such as aggregated particles, spherical particles, beaded particles, complex particles, and scale-like particles can be used. In addition, the inorganic materials include silicon oxide, calcium carbonate, titanium oxide, alumina, zirconia, aluminum silicate, mica, clay, talc, barium sulfate, etc., and the organic materials include polyimide resin, olefin or Modified olefin resins, cross-linked or non-cross-linked polystyrene resins, cross-linked or non-cross-linked acrylic resins, fluororesins, silicone resins, and other organic lubricants such as stearamide, oleic amide, and fumaric amide Mention may be made of amide compounds. In particular, in the optical filter of the present invention, from the viewpoint of minimizing light scattering caused by light loss particles and providing easy slipping performance, the average particle size of the particles is 2 μm or less and the particle concentration is 0.04 weight. % Or less is preferable. More preferably, the average particle size is 0.5 to 1.5 μm and the particle concentration is 0.02% by weight or less. As for the particle type, agglomerated silica is preferable from the viewpoint of cost and high reflectance.

  Hereinafter, the optical filter of the present invention will be described using examples.

[Methods for measuring physical properties and methods for evaluating effects]
The characteristic value evaluation method and the effect evaluation method are as follows.

(1) Lamination thickness, the number of laminations, and lamination structure The layer structure of the film was obtained by observing with an electron microscope for a sample obtained by cutting a cross section using a microtome. That is, using a transmission electron microscope HU-12 (manufactured by Hitachi, Ltd.), the cross section of the film was magnified 40000 times, a cross-sectional photograph was taken, and the layer structure and each layer thickness were measured. In some cases, in order to obtain high contrast, a staining technique using a known RuO ₄ or OsO ₄ may be used.

(2) Reflectance, transmittance, absorptivity A 60 photosphere 130-0632 (Hitachi Ltd.) and a 10 ° inclined spacer were attached to a spectrophotometer (U-3410 Spectrophotometer) manufactured by Hitachi, Ltd., and the reflectance was measured. The bandpass is set to 2 nm / servo, the gain is set to 3, and the range from 250 nm to 2600 nm is set to 120 nm / min. The scanning speed was measured. In order to standardize the reflectance, an aluminum oxide plate attached to the apparatus was used as a standard reflecting plate, and at the time of sample measurement, black paint was applied with magic ink to eliminate interference caused by reflection from the back surface. The maximum reflectance is the maximum value of the reflection spectrum at a wavelength of 250 to 2600 nm, and the wavelength is taken as the reflection wavelength. The transmittance was obtained by placing a sample in front of the integrating sphere and measuring it. Further, the absorptance in the wavelength range of 650 to 1600 nm was obtained by subtracting the reflectance and the transmittance from 100%, and the maximum value was particularly defined as the absorptivity. In addition, Examples 8 and 11 had a value of 40% or more, and all other values had an absorption rate of 1% or less.

(3) Shift amount of reflection spectrum Sample taken from the center in the film width direction to a length 4.0 × width 3.5 cm, a spectroscope USB2000 (wavelength 200-1100 nm) manufactured by Ocean Optics, An optical fiber type (ferrule type SMA905) reflection probe (R400-7-VIS / NIR) recommended by the manufacturer was connected to NIR512 (wavelength 1000-2100 nm) and light source LS-1 (tungsten / halogen lamp wavelength 360-2000 nm). Next, only the sample stage and the reflection probe (integrated light emission and light detection fiber) are installed inside a constant temperature and humidity chamber (Nagano Science Machinery Co., Ltd. LH31-14P), and a temperature-dependent reflection spectrum can be measured. The device. The measurement conditions were corrected with a reflective standard plate (WS-1) recommended by the manufacturer at an atmospheric temperature of 25 ° C., and the reflection spectrum at −5 ° C. and 65 ° C. was measured with the distance between the film and the reflective probe tip set to 5 cm. Next, the reflection spectrum data obtained for each wavelength of 0.3 nm was thinned out every three steps, and then a three-point moving average process was performed to perform a data processing process. The shift amounts at −5 ° C. and 65 ° C. of the reflection wavelength of the maximum reflectance in the reflection spectrum after the numerical processing were obtained.

(4) Optical loss The optical loss was measured using the maximum loss in the measured wavelength range in accordance with the interference filter test method JIS C5871 (1992). Here, the optical loss is an attenuation amount, and was determined according to the following equation (3).

Optical loss = −10 × log (optical output power / optical input power) (3)
The optical spectrum analyzer is 86146B manufactured by Agilent Technologies, and the light source is a broadband light source that is an option of the spectrum analyzer when the reflection wavelength is 1200 nm to 1600 nm (a combination of EELED 1.3 μm and 1.5 μm wavelength bands) When the reflection wavelength is 850 ± 10 nm, 850 nm band fixed wavelength laser 81655A manufactured by Agilent Technologies, Inc., and when the reflection wavelength is 850 nm to 400 nm, white light source AQ4305 (manufactured by Ando Electric Co., Ltd.) was used. In addition, the detection part when using 850 nm band fixed wavelength laser 81655A used the Agilent Technology Co., Ltd. 81623B power sensor.

(5) Power resistance Power resistance was evaluated using a high-output light source having a central wavelength of 1480 nm. The output of the light source used for the measurement is 500 mW, 1 W, the spot diameter φ is 1 mm, light is irradiated from the direction perpendicular to the film for 5 minutes, the thermal deformation state of the irradiated part is observed, and the following criteria are used: evaluated. Thermal deformation here refers to phenomena such as discoloration, deterioration, and melting.

Thermal deformation did not occur up to 500 mW. : △
Thermal deformation did not occur up to 1W. : ○.

(6) Unevenness of central reflection wavelength From the central part in the width direction of the film obtained by film formation, a sample of 5 m in the width direction × 4 m in the longitudinal direction was cut out, and the traveling speed was 50 cm using the spectroscope described in (3) above. Spectral reflection characteristics in the MD direction of the film per minute were collected. Reflection spectrum data was collected for about 240 seconds at a sampling rate of 1 sec. Next, with respect to the reflection spectrum data obtained every 1 sec for each wavelength of 0.3 nm, in order to remove the wavelength region that becomes noise and smooth the spectrum, it is thinned out every 3 steps, and the 3-point moving average Processing was carried out. Next, the intersection of the reflection spectrum and a straight line parallel to the wavelength axis (horizontal axis), which is half the maximum reflectance of the reflection spectrum, is wavelength 1 and wavelength 2, and the midpoint between these two points is the center wavelength of the reflection spectrum. It was. In the finally obtained time and center wavelength data, 240 seconds, that is, the value obtained by dividing the difference between the maximum value and the minimum value at 240 center reflection wavelengths by the average center wavelength is the center reflection wavelength unevenness (% ).

(7) In-plane refractive index difference between different resins, and difference between in-plane refractive index and in-plane refractive index within the same resin (Δn)
A single film was formed under the same film forming conditions as the optical filter, using the thermoplastic resin constituting the optical filter alone. In this case, the unstretched film was formed by the same method up to casting. Next, a sample is cut out from the unstretched film to a size of 10 cm × 10 cm, stretched using a biaxial stretching apparatus (Toyo Seiki Co., Ltd.), and the obtained stretched film is attached to a 20 cm × 20 cm metal frame. Then, heat treatment was performed using a tunnel oven (manufactured by Taishin Manufacturing Co., Ltd.) to obtain a single film. In addition, when the heat treatment temperature at the time of film formation was a temperature at which the thermoplastic resin was melted, it was sandwiched by a support such as a polyimide film and subjected to heat treatment in a tunnel oven. A sample was cut out from the central part of the obtained single film in the width direction of the film with a length of 4 × width of 3.5 cm, and using an Abbe refractometer 4T (manufactured by Atago Co., Ltd.), MD, TD, ZD The refractive index was determined. As a light source, a sodium D line wavelength of 589 nm was used. The average of the refractive indexes of MD and TD was defined as the in-plane refractive index, and the refractive index of ZD was defined as the surface straight refractive index. Δn, which is the difference (absolute value) between the in-plane refractive index and the in-plane refractive index, was determined as the average value of three measurements. As the immersion liquid, methylene iodide and a test piece having a refractive index of 1.74 were used. Further, the difference in in-plane refractive index between different resins was determined as the in-plane refractive index difference (absolute value) (| in-plane refractive index of thermoplastic resin A−in-plane refractive index of thermoplastic resin B |) .

(8) Layer thickness unevenness The TEM photographic image of about 40,000 times obtained in the item (1) was captured at an image size of 720 dpi using CanonScan D123U. The image is saved as a bitmap file (BMP), and then image processing software Image-Pro Plus ver. This BMP file was opened using 4 (distributor Planetron Co., Ltd.) and image analysis was performed. In the image analysis process, the relationship between the thickness in the thickness direction and the average brightness of the area sandwiched between the two lines in the width direction was read as numerical data in the vertical thick profile mode. Using the spreadsheet software (Excel2000), the position (nm) and brightness data were subjected to numerical processing of sampling step 6 (decimation 6) and 3-point moving average. Furthermore, the data obtained by periodically changing the brightness is differentiated, and the maximum value and the minimum value of the differential curve are read by the VBA program. Calculated. This operation was performed for each photograph, and the layer thicknesses of all layers were calculated. However, 20 layers from the surface layer were excluded from the evaluation. In the case of the periodic structure, as shown in the equation (4), the difference between the maximum value and the minimum value of the layer thickness was divided by the average layer thickness and multiplied by 100 to calculate the layer thickness unevenness. In the case of the inclined structure, the obtained layer thickness distribution was linearly approximated by the least square method, and the average layer thickness at each layer number was obtained. The layer thickness unevenness at each layer number was determined, and the maximum value was defined as the inclined layer thickness unevenness.
Layer thickness unevenness (%) = (maximum value of layer thickness−minimum value of layer thickness) / average layer thickness .... (4) If there is a difference in contrast between the photographs, calculation is made for each photograph. The minimum value of the uneven layer thickness was defined as the uneven layer thickness.

(9) Melt viscosity of resin The melt viscosity of resin was measured using Shimadzu Corporation Shimadzu Flow Tester CFT-500 type A. The melt temperature was 280 ° C., and after about 3 minutes from setting a chip of several g, a desired load was applied to measure the melt viscosity. Table 1 shows the results of the shear rate and melt viscosity of the thermoplastic resin used in the examples. However, the melting temperature of polybutylene terephthalate and polymethyl methacrylate was measured at 270 ° C. The desired load here is a weight of 5, 10, 15, 20 kg. Using these, the relationship between the shear rate and the melt viscosity is measured, and the melt viscosity near 125 (1 / s) is measured. Asked. When the value could not be obtained from the direct measurement result, the resin was regarded as a Newtonian material, and an approximate expression was obtained by the least square method to calculate the value.

(10) Solution viscosity (IV)
It calculated from the solution viscosity measured at 25 degreeC in orthochlorophenol. The solution viscosity was measured using an Ostwald viscometer. The unit is [dl / g]. The n number was 3, and the average value was adopted. However, only polymethylmethacrylate was not measured.

(11) Sputter deposition Sputter deposition was performed using SH-450 manufactured by ULVAC, Inc. under the film forming conditions of an ultimate vacuum of 4.5 × 10 ⁻⁶ torr and a sputtering gas Ar. The laminated thickness was adjusted while monitoring with a quartz oscillator film thickness meter. As the target, titanium oxide, niobium oxide, or SiO ₂ was used.

RF power output: 1500W
Sputtering gas: Ar
Sputtering pressure: 0.2 Pa.
[Example 1]
A polymer alloy obtained by mixing 20% by weight of polyetherimide with polyethylene terephthalate 1 is used as thermoplastic resin A, and a copolymer of PET / G-2 (polyethylene terephthalate copolymerized with 20 mol% of cyclohexanedimethanol component) is used as thermoplastic resin B. A coalescence was used (thermoplastic resins A and B, both particles-free). Thermoplastic resins A and B were melted at 280 ° C. in each extruder, passed through 5 sheets of FSS type leaf disc filters, and the discharge ratio was thermoplastic resin A composition / thermoplastic resin B with a gear pump. While weighing so that the composition = 2/1, they were merged in a 201-layer feed block to form a laminated body alternately laminated in the thickness direction. The breakdown is a laminate having a periodic structure in which the thermoplastic resin A is composed of 101 layers and the thermoplastic resin B is alternately laminated in the thickness direction, and the outermost layer is the thermoplastic resin A. Further, the thermoplastic resin C obtained by adding 0.02 wt% of aggregated silica having an average particle diameter of 1.2 μm to the thermoplastic resin A from the extruder C is joined from the pinol under the feed block so as to come to the outermost layer portion. The laminate was composed of a total of 203 layers. The cross-sectional shape of the polymer flow path at this time was a square shape having an aspect ratio (length in the width direction / length in the thickness direction) of 2. Moreover, the discharge amount of the laminated resin passing through the cross-sectional area within a unit time was 20 kg / hr / cm ² . The laminate was supplied to a T-die and formed into a sheet shape, and then rapidly cooled and solidified on a casting drum maintained at a surface temperature of 25 ° C. while applying an electrostatic applied voltage of 8 kV with a wire to obtain an unstretched film. . The draft ratio at this time was 8.

  This unstretched film is longitudinally stretched at 90 ° C. and a stretching ratio of 3.4 times, and both ends are led to a tenter gripped by clips, and 100 ° C. and transversely stretched by 4.3 times, and then heat treated at 235 ° C., TD relaxation of about 5% was performed at 120 ° C. to obtain an optical filter with a thickness of 30 μm. When the cross section of the obtained optical filter was observed, the thickness of the outermost layer of the thermoplastic resin A was 2 μm. The average layer thickness of the A layer was 173 nm, and the average layer thickness of the B layer was 87 nm. Table 2 shows the physical property results of the obtained optical filter. It was confirmed that the optical filter had high light blocking performance and excellent thermal stability of optical performance. Note that the difference Δn between the in-plane refractive index and the in-plane refractive index when the thermoplastic resin B was formed alone was 0.023. Moreover, the thermoplastic resin A was 0.158. The in-plane refractive index difference between the in-plane refractive index of the thermoplastic resin A and the in-plane refractive index of the thermoplastic resin B was 0.082.

[Example 2]
Polyethylene terephthalate 2 added with 0.04% by weight of agglomerated silica in advance is used as thermoplastic resin A, and thermoplastic resin B is PET / I-1 (polyethylene terephthalate copolymerized with 17.5 mol% of isophthalic acid component). A copolymer was used (thermoplastic resin B, no particles). Thermoplastic resins A and B were melted at 280 ° C. in each extruder, passed through 5 sheets of FSS type leaf disc filters, and the discharge ratio was thermoplastic resin A composition / thermoplastic resin B with a gear pump. While weighing so that the composition = 2/1, they were merged in a 201-layer feed block to form a laminate in which 201 layers were alternately laminated in the thickness direction. The breakdown is a laminate having a periodic structure in which the thermoplastic resin A is composed of 101 layers and the thermoplastic resin B is alternately laminated in the thickness direction, and the outermost layer is the thermoplastic resin A. The cross-sectional shape of the polymer flow path at this time was a square shape with an aspect ratio (length in the width direction / length in the thickness direction) of 1. Moreover, the discharge amount of the laminated resin passing through the cross-sectional area within the unit time was 35 kg / hr / cm ² . The laminate was supplied to a T-die and formed into a sheet shape, and then rapidly cooled and solidified on a casting drum maintained at a surface temperature of 25 ° C. while applying an electrostatic applied voltage of 8 kV with a wire to obtain an unstretched film. . The draft ratio at this time was 15.
This unstretched film is longitudinally stretched at 120 ° C. and a stretching ratio of 3.3 times, and both ends are led to a tenter gripped with clips, and 100 ° C. and 4.3 times laterally stretched, followed by heat treatment at 220 ° C., An optical filter having a thickness of 26 μm was obtained without performing TD relaxation. Table 2 shows the physical property results of the obtained optical filter. It was confirmed that the optical filter had light blocking performance and excellent thermal stability of optical performance. Note that the difference Δn between the in-plane refractive index and the in-plane refractive index when the thermoplastic resin B was formed alone was 0.06. (Hereinafter, Δn of the thermoplastic resin A was 0.14 or more.) The in-plane refractive index difference between the in-plane refractive index of the thermoplastic resin A and the in-plane refractive index of the thermoplastic resin B was 0.062. Met.

[Example 3]
Polyethylene terephthalate 1 to which 0.04% by weight of agglomerated silica was added in advance was used as thermoplastic resin A, and PET / G-1 (polyethylene terephthalate copolymerized with 33 mol% of cyclohexanedimethanol component) was used as thermoplastic resin B. A polymer was used. (Thermoplastic resin B is particle-free). Thermoplastic resins A and B were melted at 280 ° C. in each extruder, passed through 5 sheets of FSS type leaf disc filters, and the discharge ratio was thermoplastic resin A composition / thermoplastic resin B with a gear pump. While weighing so that the composition = 1/1, they were merged in a 201-layer feed block to form a laminate in which 201 layers were alternately laminated in the thickness direction. The breakdown is a laminate having a periodic structure in which the thermoplastic resin A is 101 layers and the thermoplastic resin B is alternately laminated in the thickness direction consisting of 100 layers, and the layer thickness of the outermost layer of the thermoplastic resin A is: The thickness of other thermoplastic resin layers was 20 times. The cross-sectional shape of the polymer flow path at this time was a square shape having an aspect ratio (length in the width direction / length in the thickness direction) of 1.5. Moreover, the discharge amount of the laminated resin passing through the cross-sectional area within a unit time was 10 kg / hr / cm ² . The laminate was supplied to a T-die and formed into a sheet shape, and then rapidly cooled and solidified on a casting drum maintained at a surface temperature of 25 ° C. while applying an electrostatic applied voltage of 8 kV with a wire to obtain an unstretched film. . The draft ratio at this time was 5.

  This unstretched film was longitudinally stretched at 90 ° C. and a stretching ratio of 3.6 times, led to a tenter that grips both ends with clips, 100 ° C. and 4.3 times transversely stretched, and then heat treated at 235 ° C., About 5% TD relaxation was performed at 120 ° C. to obtain a laminated film having a thickness of 30.2 μm. When the cross section of the obtained optical filter was observed, the thickness of the outermost layer of the thermoplastic resin A was 2 μm. The average layer thickness of the A layer was 130 nm, and the average layer thickness of the B layer was 133 nm. Note that the difference Δn between the in-plane refractive index and the in-plane refractive index when a thermoplastic resin film was formed alone was 0.02. The in-plane refractive index difference between the in-plane refractive index of the thermoplastic resin A and the in-plane refractive index of the thermoplastic resin B was 0.082.

Furthermore, by sputter deposition, first, SiO ₂ was deposited at 145 nm on the laminated film, and then niobium oxide was deposited at 92 nm to obtain a total of 203 optical filters. Table 2 shows the physical property results of the obtained optical filter. It was confirmed that the optical filter had high light blocking performance and excellent thermal stability of optical performance.

[Example 4]
A laminated film having a thickness of 43.3 μm was obtained in the same manner as in Example 3 except that the number of laminated layers was 301. Table 2 shows the physical property results of the obtained optical filter. It was confirmed that the optical filter had light blocking performance and excellent thermal stability of optical performance. The difference Δn between the in-plane refractive index and the in-plane refractive index when the thermoplastic resin B was formed alone was 0.025. (Hereinafter, Δn of each of the thermoplastic resins B in Examples 5 to 13 was 0.03 or less.) In-plane refractive index of the thermoplastic resin A and in-plane refractive index of the thermoplastic resin B The refractive index difference was 0.081.

[ Reference Example 1 ]
Polyethylene terephthalate 2 is used as the thermoplastic resin A, PBT (polybutylene terephthalate) is used as the thermoplastic resin B, and the discharge amount of the laminated resin passing through the cross-sectional area within a unit time is 15 kg / An optical filter having a thickness of 26 μm was obtained in the same manner as in Example 2 except that hr / cm 2 and the stretching temperature were set to 110 ° C. Table 2 shows the physical property results of the obtained optical filter. It was confirmed that the optical filter had light blocking performance and excellent thermal stability of optical performance. The in-plane refractive index difference between the in-plane refractive index of the thermoplastic resin A and the in-plane refractive index of the thermoplastic resin B was 0.06.

[Example 6]
Polyethylene terephthalate 2 is used as the thermoplastic resin A, PET / G-2 (polyethylene terephthalate copolymerized with 20 mol% of cyclohexanedimethanol component) is used as the thermoplastic resin B, and the cross-sectional area is within a unit time. An unstretched film was obtained in the same manner as in Example 3 except that the amount of the laminated resin that passed through was 25 kg / hr / cm ² and the draft ratio was 10. Next, this unstretched film was longitudinally stretched at 110 ° C. and a stretching ratio of 3.6 times, and both ends were led to a tenter gripped by clips, and 100 ° C. and 4.3 times transverse stretched, and then heat treated at 235 ° C. And about 5% TD relaxation was performed at 120 ° C. to obtain an optical filter having a thickness of 29 μm. Table 2 shows the physical property results of the obtained optical filter. It was confirmed that the optical filter had high light blocking performance and excellent thermal stability of optical performance. The in-plane refractive index difference between the in-plane refractive index of the thermoplastic resin A and the in-plane refractive index of the thermoplastic resin B was 0.081. (Hereinafter, the in-plane refractive index difference between the in-plane refractive index of the thermoplastic resin A and the in-plane refractive index of the thermoplastic resin B in Examples 7 to 13 was 0.08 or more.)
[Example 7]
An unstretched film was obtained in the same manner as in Example 3 except that the discharge amount of the laminated resin passing through the cross-sectional area within a unit time was 20 kg / hr / cm ² and the draft ratio was 10. Next, this unstretched film was longitudinally stretched at 95 ° C. and a stretching ratio of 3.6 times, and both ends were led to a tenter gripped by clips, and 100 ° C. and 4.3 times transversely stretched, followed by heat treatment at 235 ° C. And about 5% TD relaxation was performed at 120 ° C. to obtain an optical filter having a thickness of 29 μm. Table 2 shows the physical property results of the obtained optical filter. It was confirmed that the optical filter had high light blocking performance and excellent thermal stability of optical performance.

[Example 8]
A laminated film having a thickness of 29 μm was obtained in the same manner as in Example 6 except that the stretching temperature was 95 ° C.

  Furthermore, 0.2% by weight of paliogen black S0084, which is a perylene organic pigment manufactured by BASF, was dissolved in acetone, and applied to the surface of the laminated film with a layer thickness of 1 μm using a metabar. Furthermore, heat treatment was performed at 150 ° C. for 10 minutes to obtain an optical filter. Table 2 shows the physical property results of the obtained optical filter. It was confirmed that the optical filter had high light blocking performance in the near-infrared region having a wavelength of 750 nm or more and excellent in thermal stability of optical performance.

[Example 9]
Polyethylene terephthalate 2 added with 0.04% by weight of agglomerated silica in advance was used as thermoplastic resin A, and PET / G-2 (polyethylene terephthalate copolymerized with 20 mol% of cyclohexanedimethanol component) was used as thermoplastic resin B. A polymer was used. (Thermoplastic resin B is particle-free). Thermoplastic resins A and B were melted at 280 ° C. in each extruder, passed through 5 sheets of FSS type leaf disc filters, and the discharge ratio was thermoplastic resin A composition / thermoplastic resin B with a gear pump. While weighing so that the composition = 2/1, they were merged in a 201-layer feed block to form a laminate in which 201 layers were alternately laminated in the thickness direction. The breakdown is a laminate having a periodic structure in which the thermoplastic resin A is composed of 101 layers and the thermoplastic resin B is alternately laminated in the thickness direction, and the thermoplastic resin A is the outermost layer. . The cross-sectional shape of the polymer flow path at this time was a square shape having an aspect ratio (length in the width direction / length in the thickness direction) of 1.5. Moreover, the discharge amount of the laminated resin passing through the cross-sectional area within a unit time was 20 kg / hr / cm ² . The laminate was supplied to a T-die and formed into a sheet shape, and then rapidly cooled and solidified on a casting drum maintained at a surface temperature of 25 ° C. while applying an electrostatic applied voltage of 8 kV with a wire to obtain an unstretched film. . The draft ratio at this time was 7.
This unstretched film was longitudinally stretched at 90 ° C. and a stretching ratio of 3.6 times, led to a tenter that grips both ends with clips, 100 ° C. and 4.3 times transversely stretched, and then heat treated at 235 ° C., TD relaxation of about 5% was performed at 120 ° C. to obtain a laminated film having a thickness of 44 μm. When the cross section of the obtained optical filter was observed, the average layer thickness of the A layer was 317 nm, and the average layer thickness of the B layer was 160 nm. Table 2 shows the physical property results of the obtained optical filter. It was confirmed that the optical filter had high light blocking performance and excellent thermal stability of optical performance.

[Example 10]
A laminated film having a thickness of 41 μm was obtained in the same manner as in Example 9 except that the discharge amount of the laminated resin passing through the cross-sectional area within a unit time was 15 kg / hr / cm ² . When the cross section of the obtained optical filter was observed, the average layer thickness of the A layer was 267 nm, and the average layer thickness of the B layer was 134 nm.

Furthermore, by sputter deposition, first, SiO ₂ was deposited to 112 nm on the laminated film, and then titanium oxide was deposited to 70 nm to obtain a total of 203 optical filters. Table 2 shows the physical property results of the obtained optical filter. It was confirmed that the optical filter had high light blocking performance and excellent thermal stability of optical performance.

[Example 11]
An optical filter having a thickness of 19 μm was obtained in the same manner as in Example 7 except that 1% by weight of Dainippon Ink Co., Ltd. Cyanine Blue (LA-50) was added to the thermoplastic resin A. When the cross section of the obtained optical filter was observed, the thickness of the layer of the thermoplastic resin A was 1.5 μm. The average layer thickness of the A layer was 82 nm, and the average layer thickness of the B layer was 87 nm.
Table 2 shows the physical property results of the obtained optical filter. It was confirmed that the optical filter had high light blocking performance over a wavelength range of 500 nm to 800 nm and was excellent in thermal stability of optical performance.

[Example 12]
Polyethylene terephthalate 1 to which 0.04% by weight of agglomerated silica was added in advance was used as thermoplastic resin A, and PET / G-2 (polyethylene terephthalate copolymerized with 20 mol% of cyclohexanedimethanol component) was used as thermoplastic resin B. A polymer was used. (Thermoplastic resin B is particle-free). Thermoplastic resins A and B were melted at 280 ° C. in each extruder, passed through 5 sheets of FSS type leaf disc filters, and the discharge ratio was thermoplastic resin A composition / thermoplastic resin B with a gear pump. While being measured so that the composition = 1/1, they were merged in a 801-layer feed block to obtain a laminate in which 801 layers were alternately laminated in the thickness direction. The breakdown is a laminate having a periodic structure in which 401 layers of thermoplastic resin A and 400 layers of thermoplastic resin B are alternately laminated in the thickness direction, and the layer thickness of the outermost layer of thermoplastic resin A is as follows: The thickness of other thermoplastic resin layers was 20 times. The cross-sectional shape of the polymer flow path at this time was a square shape having an aspect ratio (length in the width direction / length in the thickness direction) of 1.5. Moreover, the discharge amount of the laminated resin passing through the cross-sectional area within a unit time was 20 kg / hr / cm ² . Further, the thermoplastic resin C obtained by adding 0.06% by weight of aggregated silica having an average particle diameter of 1.2 μm to the thermoplastic resin A from the extruder C is joined from the pinol under the feed block so as to come to the outermost layer portion. The laminate was composed of a total of 803 layers. The laminate was supplied to a T-die and formed into a sheet shape, and then rapidly cooled and solidified on a casting drum maintained at a surface temperature of 25 ° C. while applying an electrostatic applied voltage of 8 kV with a wire to obtain an unstretched film. . The draft ratio at this time was 10.

  This unstretched film is longitudinally stretched at 90 ° C. and a stretching ratio of 3.5 times, and both ends are led to a tenter that is gripped by clips, and 100 ° C. and 4.3 times transversely stretched, and then heat treated at 235 ° C., TD relaxation of about 5% was performed at 120 ° C. to obtain an optical filter having a thickness of 83 μm. When the cross section of the obtained optical filter was observed, the sum of the thickness of the pinole layer and the thick layer of the thermoplastic resin A, which was the outermost layer, was 3.5 μm. Further, both the A layer and the B layer had an inclined structure in which the layer thickness was continuously changed from 76 to 110 nm. Table 2 shows the physical property results of the obtained optical filter. It was confirmed that the optical filter had high light blocking performance over a wavelength range of 500 nm to 700 nm and was excellent in thermal stability of optical performance.

[Example 13]
A laminated film having a thickness of 130 μm was obtained in the same manner as in Example 12 except that the discharge amount of the laminated resin passing through the cross-sectional area within a unit time was 35 kg / hr / cm ² and no pinole was used. . When the cross section of the obtained optical filter was observed, the sum of the thickness of the pinole layer and the thick layer of the thermoplastic resin A, which was the outermost layer, was 3.5 μm. Further, the layer A had a gradient structure in which the layer thickness was continuously changed from 124 to 180 nm, and the layer B was from 130 to 190 nm.

Furthermore, by sputtering deposition, first, SiO ₂ was deposited at 175 nm on the laminated film, and then the process of depositing titanium oxide at 109 nm was repeated twice to obtain a total of 805 optical filters. Table 2 shows the physical property results of the obtained optical filter. It was confirmed that the optical filter had high light blocking performance over a wavelength range of 850 nm to 1200 nm and was excellent in thermal stability of optical performance.

[Comparative Example 1]
Polyethylene terephthalate 3 to which 0.04% by weight of agglomerated silica was added in advance was used as thermoplastic resin A, and PET / G-1 (polyethylene terephthalate copolymerized with 20 mol% of cyclohexanedimethanol component) was used as thermoplastic resin B. A polymer was used (thermoplastic resin B, no particles). Thermoplastic resins A and B were melted at 280 ° C. in respective extruders, passed through a wire mesh filter, and the discharge ratio was thermoplastic resin A composition / thermoplastic at screw rotation speed without a gear pump. While weighing so that the resin B composition = 3/1, 201 layers of feed blocks were combined to form a laminate in which 201 layers were alternately laminated in the thickness direction. The breakdown is a laminate having a periodic structure in which the thermoplastic resin A is composed of 101 layers and the thermoplastic resin B is alternately laminated in the thickness direction, and the outermost layer is the thermoplastic resin A. The cross-sectional shape of the polymer flow path at this time was a square shape with an aspect ratio (length in the width direction / length in the thickness direction) of 1. Moreover, the discharge amount of the laminated resin passing through the cross-sectional area within the unit time was 35 kg / hr / cm ² . The laminate was supplied to a T-die and formed into a sheet shape, and then rapidly cooled and solidified on a casting drum maintained at a surface temperature of 25 ° C. while applying an electrostatic applied voltage of 8 kV with a wire to obtain an unstretched film. . The draft ratio at this time was 20.
This unstretched film is longitudinally stretched at 125 ° C. and a stretching ratio of 3.0 times, led to a tenter that grips both ends with clips, 100 ° C. and 4.3 times laterally stretched, and then subjected to heat treatment at 220 ° C., TD relaxation was carried out at 120 ° C. for 5% to obtain an optical filter with a thickness of 26 μm. Table 2 shows the physical property results of the obtained optical filter. It was confirmed that the optical filter had no light blocking performance. Note that the difference Δn between the in-plane refractive index and the in-plane refractive index when the thermoplastic resin B was formed alone was 0.05. The in-plane refractive index difference between the in-plane refractive index of the thermoplastic resin A and the in-plane refractive index of the thermoplastic resin B was 0.05.

[Comparative Example 2]
Polyethylene terephthalate 3 to which 0.04% by weight of agglomerated silica is added in advance is used as thermoplastic resin A, and PET / I-2 (polyethylene terephthalate copolymerized with 12 mol% of isophthalic acid component) is used as thermoplastic resin B. A coalescence was used (thermoplastic resin B, no particles). Thermoplastic resins A and B were melted at 280 ° C. in respective extruders, passed through a wire mesh filter, and the discharge ratio was thermoplastic resin A composition / thermoplastic at screw rotation speed without a gear pump. While weighing so that the resin B composition = 3/1, 201 layers of feed blocks were combined to form a laminate in which 201 layers were alternately laminated in the thickness direction. The breakdown is a laminate having a periodic structure in which the thermoplastic resin A is composed of 101 layers and the thermoplastic resin B is alternately laminated in the thickness direction, and the outermost layer is the thermoplastic resin A. The cross-sectional shape of the polymer flow path at this time was a square shape with an aspect ratio (length in the width direction / length in the thickness direction) of 1. Moreover, the discharge amount of the laminated resin passing through the cross-sectional area within a unit time was 30 kg / hr / cm ² . The laminate was supplied to a T-die and formed into a sheet shape, and then rapidly cooled and solidified on a casting drum maintained at a surface temperature of 25 ° C. while applying an electrostatic applied voltage of 8 kV with a wire to obtain an unstretched film. . The draft ratio at this time was 20.
This unstretched film was longitudinally stretched at 110 ° C. and a stretching ratio of 3.3 times, led to a tenter that grips both ends with clips, and then stretched at 100 ° C. and 4.3 times, and then heat treated at 220 ° C., An optical filter having a thickness of 44 μm was obtained without performing TD relaxation. Table 2 shows the physical property results of the obtained optical filter. It was confirmed that the optical filter had no light blocking performance. The difference Δn between the in-plane refractive index and the in-plane refractive index when the thermoplastic resin B was formed alone was 0.12.
The in-plane refractive index difference between the in-plane refractive index of the thermoplastic resin A and the in-plane refractive index of the thermoplastic resin B was 0.03.

[Comparative Example 3]
Polybutylene terephthalate added with 0.04% by weight of agglomerated silica in advance was used as the thermoplastic resin A, and polymethyl methacrylate was used as the thermoplastic resin B (thermoplastic resin B, no particles). Thermoplastic resins A and B were melted at 270 ° C. in respective extruders, passed through a wire mesh filter, and the discharge ratio was thermoplastic resin A composition / thermoplastic at a screw rotation speed without a gear pump. While weighing so that the resin B composition = 4/1, it was merged in a 201-layer feed block to obtain a laminate in which 153 layers were alternately laminated in the thickness direction. The breakdown is a laminate having a periodic structure in which 77 layers of thermoplastic resin A and 76 layers of thermoplastic resin B are alternately stacked in the thickness direction, and the outermost layer is thermoplastic resin A. In this case, the cross-sectional shape of the polymer flow path was a circular shape. Moreover, the discharge amount of the laminated resin passing through the cross-sectional area within a unit time was 30 kg / hr / cm ² . After supplying the laminate to a T-die and forming it into a sheet shape, it was rapidly cooled and solidified on a casting drum maintained at a surface temperature of 25 ° C. while applying an electrostatic applied voltage of 8 kV with a wire, and unstretched with a thickness of 20 μm. A film was obtained. The draft ratio at this time was 20.
Table 2 shows the physical property results of the optical filter obtained without stretching. It was confirmed that the optical filter had low light blocking performance and caused a wavelength shift depending on temperature. The in-plane refractive index difference between the in-plane refractive index of the thermoplastic resin A and the in-plane refractive index of the thermoplastic resin B was 0.08.

The present invention relates to an optical filter. In more detail, it is a display, an optical sensor, a solar cell, optical information communication, and an optical filter in the field of decorative materials. In particular, a gain equalizing filter (GFF: Gain Flattening Filter) in an optical measurement and optical information communication, a narrow band. The present invention relates to an optical filter suitable for a transmission filter (NBPF: Narrow Bandpass Filter).

Top view of the feed block Side view of slit plate in feed block Front view of feed block Extrusion configuration

Explanation of symbols

1: Polymer A
2: Polymer B
3: Slit plate 4: Manifold 5: Feed block 6: Slit part 7 into which polymer A flows in 7: Slit part into which polymer B flows in 8: Short pipe 9: Base 10: Cast drum 11: Filter pack 12: Gear pump 13: Feed Block 14: Pinole 15: Base

Claims (6)

A thermoplastic resin A layer comprising polyethylene terephthalate and a thermoplastic resin B layer comprising a copolyester are laminated in a thickness direction of 100 layers or more, and the layer thickness unevenness is 20% or less. The thermoplastic resin B layer The intrinsic viscosity measured in the orthochlorophenol of the thermoplastic resin B constituting is 0.64 or less, the maximum value of transmittance or reflectance at a wavelength of 250 to 2600 nm is 70% or more, and −5 ° C. An optical filter having a reflection spectrum or transmission spectrum shift amount of 10 nm or less in an atmosphere at 65 ° C. The optical filter according to claim 1, wherein at least one inorganic material layer having a thickness of 500 nm or less is laminated. The optical filter according to claim 1 or 2 , wherein a pigment is contained in at least one thermoplastic resin layer. The optical filter according to claim 1, wherein the in-plane refractive index difference between the thermoplastic resin A layer and the thermoplastic resin B layer is 0.08 or more. Light measuring passive optical element comprising an optical filter according to any one of claims 1-4. Optical information communication passive optical element comprising an optical filter according to any one of claims 1-4.

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