JP2007219396A - Nd filter for high-intensity light source and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ND filter capable of controlling light quantity in an ND value range of 0-4.5 in the infrared light region and in an ND value range of 0-6 in the visible light region, and a method for producing the same. <P>SOLUTION: A light shielding pattern is formed using a laminate of a film of a metal nanoparticle ink prepared by dispersing metal nanoparticles and a film of a dye ink which absorbs ≥90% of light from a light source, or a film of a mixed ink comprising a metal nanoparticle ink and a dye ink having ability to form a monolayer film which absorbs ≥90% of light from a light source. A light shielding pattern having continuously varying density can be formed by an ink jet system. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ND filter for a high-intensity light source used in an optical distance measuring device, an optical copying device, or the like using metal fine particles, and a manufacturing method thereof.

  Conventionally, as a light amount adjusting member of an optical device, a member that adjusts a diameter of a hole through which light passes by adjusting a diaphragm blade of a diaphragm device, a member that uses an ND (Neutral Density) filter, or a combination thereof, etc. Are known.

  The use of such an ND filter is not limited to simple light quantity adjustment, but for example, for the purpose of measuring a moving distance and a rotation angle, a light source whose transmittance is continuously changed according to the distance and the rotation angle is used. The current moving distance and the rotation angle are measured by detecting the amount of light transmitted through the ND filter.

Conventionally, the following are known as such ND filters.
(1) A metal film or dielectric film formed into a single layer or multiple layers by vapor deposition.
(2) A material in which a pigment or dye that absorbs light is incorporated into a glass or transparent film forming material.
(3) Glass or transparent film coated with light absorbing pigment or dye.
(4) A film using a silver salt film.

However, these ND filters have the following problems.
First, the ND filter in which a film is formed by vapor deposition of (1) has a problem that the manufacturing apparatus becomes large and the manufacturing process becomes complicated, so that the productivity is low. There is a problem that becomes complicated.

  In addition, the ND filter obtained by kneading or applying pigments or dyes to the glass or transparent film of (2) and (3) has a problem that it is difficult to provide an accurate concentration gradient. is there. In addition, since an ND filter in which a pigment or a dye is kneaded has a high light transmittance, it is difficult to obtain a high ND value for a high-intensity light source.

  The ND filter using the silver salt film of (4) can give a high-precision density gradient, but has a high ND value for adjusting the light quantity of the high-intensity light source, for example, an ND value of 6 (transmittance of 100 There is a problem that it is difficult to manufacture an ND filter having a density of 1 / 10,000.

  In order to measure a moving distance and a rotation angle with a high accuracy and a wide range by using such an ND filter, as the ND filter, the transmittance is low (the ND value is low) and the transmittance is low (the ND value is high). It is necessary to use a high-intensity light source using what is covered.

  In general, there is no problem in places where the light transmittance is high because the application amount of the light-shielding ink can be reduced or the concentration can be lowered, but the ND value is 6 (transmittance is 1 / 1,000,000). It is difficult to manufacture an ND filter having a high density.

  As described above, in the light amount adjustment for the high-intensity light source, the ND filter according to the conventional manufacturing method has low productivity, and it is difficult to achieve a high ND value with high reliability. In realization, further technical improvements are required for the ND filters used in these high-intensity light sources.

  As described above, conventionally, as a light amount adjusting member in general optical devices, a method of adjusting a diaphragm blade in a diaphragm device, a method using an ND filter, or a method combining these is known. However, it was difficult to manufacture a device that can be used for adjusting the amount of light with high resolution. In addition, an ND filter in which a metal film or a dielectric film is formed in a single layer or a multilayer by vapor deposition or the like can provide sufficient light shielding performance, but the number of manufacturing processes increases, and the cost of equipment increases, and the productivity also decreases. was there.

  The present invention has been made to solve the above-mentioned conventional problems, and it is possible to adjust the light amount to a high resolution range with an ND value of 0 to 4.5 in the infrared light region and an ND value of 0 to 6 in the visible light region. An object of the present invention is to provide an ND filter and a manufacturing method thereof.

  In order to solve the above-mentioned problems, the inventors of the present invention have developed an ND for a high-intensity light source, in which a coating layer of metal fine particle ink in which metal fine particles are dispersed on a transparent substrate and a coating layer of black dye ink are applied in layers. The present invention was completed by finding that a filter or a ND filter for a high-intensity light source formed by applying a mixed ink of fine metal particle ink and black dye ink on a transparent substrate can solve the above-mentioned conventional problems. It came to do.

  The ND filter for a high-intensity light source according to the present invention is an ND filter formed by forming an ink application layer that absorbs light from a light source on a transparent substrate, and the ink application layer that absorbs light from the light source includes: It is characterized by comprising a coating film of a metal fine particle ink in which metal fine particles are dispersed and a coating film of a dye ink that absorbs 90% or more of light from a light source.

  In addition, the ND filter for a high-intensity light source according to the present invention has a single-layer coating film forming ability that absorbs 90% or more of the light from the metal fine particle ink and the light source on the transparent substrate, instead of the laminated structure as described above. The coating film may be formed using a mixed ink with a dye ink having

  In the present invention, it is preferable that the weight ratio of the metal fine particles and the other components including the dye in the coating layer of the ink that absorbs light from the light source is in a range of 100: 1 to 100.

  The transparent base material used in the present invention may be either inorganic or organic, and the shape may be any of a solid shape such as a molded product, a plate shape, or a film shape. Good. Such transparent substrates include polyester, polyethersulfone, polyvinylidene chloride, polyvinyl chloride, polyethylene, polypropylene, polycarbonate, acrylic resin, glass or other plate or film, thermoplastic resin and glass fiber. Examples thereof include a molded product made of an organic binder and an inorganic filler.

  In addition, the transparent substrate of the present invention having 1 nm to 100 nm pores for holding the ink layer on the surface enhances the adhesion of the light shielding pattern due to the anchor effect, and is more reliable ND. A filter can be produced. Such pores can modify the surface of the transparent substrate itself, or can be formed on the surface of the transparent substrate as a transparent layer having a thickness of 1 μm or more made of an organic compound, an inorganic compound or a composite thereof. For example, it can be easily formed by applying and drying a paint in which organic or inorganic fine particles are dispersed in a binder resin solution on the surface of the transparent substrate. In this case, the size and density of the pores can be easily adjusted by changing the ratio of the particle size of the fine particles to the binder resin.

  Furthermore, when the transparent substrate is, for example, a glass plate, pores can be formed also by an etching method in which the surface of the surface is treated with hydrofluoric acid vapor. .

  In the present invention, when the metal fine particle ink and the dye ink are applied on the transparent substrate having the ink receiving layer as described above, the dye ink is absorbed into the receiving layer through the pores and cannot enter the pores. The metal fine particle ink having a particle size forms a film on the surface of the receiving layer. As a result, there are very few pinholes in the film formed of the dye ink and the metal fine particle ink, and a high-concentration ND filter can be manufactured.

  The pore diameter in the transparent layer having pores is very important. For example, when the pore diameter is 1 nm or less, such a permeation layer of the dye ink layer is not formed. On the other hand, if the pore diameter is too large, the fine metal particles are filled in the fine pores, making it difficult for the fine metal particles to be arranged on the surface. As a result, efficient light shielding performance cannot be obtained. Therefore, the pore size for rapidly obtaining an ND filter having a light shielding performance is adjusted to be in the range of 1 nm to 100 nm, preferably 1 nm to 10 nm.

    The metal fine particle ink according to the present invention includes Au, Pt, Ag, Cu, Ni, Cr, Rh, Pd, Zn, Co, Mo, Ru, W, Os, Ir, Fe, Mn, Ge, Sn, Ga, Al. It is obtained by dispersing at least one metal fine particle selected from Ti, V, Ta and In in water or an organic solvent. As the metal fine particles to be used, Ag, Au, Pt, Ni, Cr, Sn and the like are particularly desirable.

  As the above metal fine particles, clusters of metal particles obtained by vapor deposition or sputtering, metal fine particles obtained by decomposing organometallic particles, or precipitated by adding a reducing agent in a solution containing metal ions. Metal fine particles produced by coating metal fine particles with a protective film are suitable. The metal fine particles coated with the protective film are very stably dispersed in water or an organic solvent. Among the metal fine particles coated with these protective films, the metal fine particles coated with the protective film in which the metal fine particles are deposited by adding a reducing agent in a solution containing metal ions are particularly water, alcohol or acrylic monomers. Provides a stable dispersion in a hydrophilic dispersion medium. Silver fine particles, one of the typical metal fine particles, are gradually dropped by adding a tertiary amine to a silver nitrate aqueous solution coexisting with a dispersant such as a comb polymer. Thus, it is obtained by precipitating silver particles. A protective colloid layer is immediately formed by adsorbing the comb polymer on the surface of the precipitated silver fine particles, and a dispersion of sharp silver fine particles having a particle size range of 1 to 100 nm and an average particle size of about 20 nm is obtained. Can be easily obtained. The obtained silver fine particle liquid is used after being concentrated to a desired concentration after removing nitrate ions and excess comb polymer by ultrafiltration, for example.

  The dispersibility of the metal fine particles obtained in this way is very stable and does not cause problems such as aggregation or precipitation and solidification even when stored for 1 year or more in a sealed state at room temperature. Even if it is a minute, since it shows a low viscosity, a high concentration metal fine particle ink can be used also in an inkjet printer.

  From the viewpoints of light-shielding properties and dispersion stability, the metal fine particles have a particle size of 0.5 to 300 nm, preferably 1 to 100 nm, and are prepared with particles having a particle size smaller than 0.5 nm. In the case of the metal fine particle ink, sufficient light shielding properties cannot be obtained, and in the case of the metal fine particle ink made of particles having a particle diameter larger than 300 nm, it is difficult to maintain the dispersion stability of the particles.

  In addition, the metal fine particle ink in which the metal fine particles colored in black or the like are dispersed by treating the metal fine particles in advance with oxidation or sulfurization can obtain more effective light shielding performance.

  The black dye ink is at least one black selected from direct dyes, acid dyes, basic dyes, disperse dyes, reactive dyes, mordanting / acidic mordant dyes, azoic dyes, sulfurized / sulfurized vat dyes, and vat dyes. It is obtained by dispersing a dye in water or an organic solvent. As the black dye to be used, a direct dye system, an acid dye system, a disperse dye system, a reactive dye system and the like are particularly desirable. The black dye ink is prepared so as to contain 1 to 40 parts by weight of at least one of these dyes with respect to 100 parts by weight of the dispersion medium and the solvent. In the case where the light source has a hue of a specific wavelength, a dye having a hue other than the black dye can be used as long as the dye absorbs at least 99% of the wavelength specific to the light source instead of the black dye.

  Usually, the ink is adjusted so that the metal fine particles contain 1 wt% to 50 wt%, preferably 5 wt% to 30 wt%, and the black dye contains 1 wt% to 30 wt%, preferably 3 wt% to 10 wt%. Viscosity of those dispersed in an organic solvent such as alcohol or alcohol is 10 cP or less, and is suitable for application using an ink jet apparatus. When it is applied using a printing plate, the viscosity is too low, so it is mixed with a water-soluble resin or resin emulsion and the viscosity is adjusted to the range of 10 cP to 200 cP.

  As an application method for applying the ink to the surface of the transparent substrate to form a light-shielding pattern, electrostatic coating printing, ink jet printing, electrophotographic printing, intaglio printing, etc. can be applied. A controllable ink jet device is preferred. The ink jet apparatus can use either a thermal method or a piezo method. As a method for creating an ND filter by an ink jet device, a light shielding pattern having a desired shade is applied on a transparent base material according to the amount of ink ejected from the ink jet device. The ink to be applied can be applied by discharging the metal fine particle ink and the black dye ink from individual or the same ink cartridge. Incidentally, the amount of ink ejected by the ink jet method can be controlled with very high precision by computer control.For example, a pre-prepared original pattern is read by a scanner, and a print pattern is faithfully printed on a transparent substrate. Can be formed. Unlike other printing methods, once a pattern is read, even a single sheet can be printed on a transparent substrate without requiring special work setup.

  Intaglio printing is usually used for printing plates for gravure printing, and the ND filter for a high-intensity light source of the present invention can be produced by this method, but is not necessarily limited to such a method. Absent. In other words, an appropriate amount of ink is supplied to the intaglio printing plate according to the amount of ink absorbed by the substrate, and the plate is pressed against the surface of the transparent substrate to form a light-shielding pattern comprising an ink layer having a desired thickness on the substrate. It is also possible to form

  The light shielding pattern of the ND filter formed by various methods in this manner is fixed to the transparent substrate by natural drying, irradiation with ultraviolet rays or heat rays. If there are pores on the surface of the transparent substrate, the amount of ink applied will not overflow from the pores because the amount of resin binder and resin emulsion that has penetrated into the pores at the time of fixing exceeds the pore absorption capacity. Adjust to the amount. In the light-shielding pattern after the drying / fixing process obtained in this way, metal fine particles having a light-shielding effect are arranged on the surface of the applied pattern. When pores exist on the surface, they exist in the pores. An ink pattern containing only metal fine particles cannot provide a sufficient light-shielding effect for a high-intensity light source due to the pinhole and ink layer thickness. Produce high-resolution ND filters that can adjust light quantity with high resolution, with ND values of 0 to 4.5 in the light region and ND values of 0 to 6 in the visible light region, with high productivity in a low-cost manufacturing process. be able to.

  The pattern of the coating film which comprises the light shielding film in this invention can be made into various patterns by a use.

  For example, when used for applications such as detection of moving distance, a band-like pattern with a continuously changing concentration, an arc-shaped, open spiral or radial pattern with a continuously changing concentration for detecting a rotation angle, In addition, it can be formed in an arbitrary shape such as a bar code shape, a dotted shape, or a circular shape whose density continuously changes from the center to the outside.

According to the present invention, it is possible to easily manufacture an ND filter having a wide density gradient with an ND value of 0 to 6.3 in the visible light region and an ND value of 0 to 4.6 in the infrared light region. For example, to prepare a ND filter on both sides of a transparent substrate, by overlaying two sheets, it is also possible broad light amount adjusting of 10 ¹¹ times the order of ND values 0 to 11. In addition, since the metal fine particle ink is used, application as an ND filter for a high-intensity light source of a light source having a longer wavelength can be expected.

  Examples of the present invention will be described below.

  On a transparent substrate formed by forming a 30 μm thick porous film mainly composed of alumina fine particles as an ink receiving layer on a PET transparent film having a thickness of 0.1 mm, Ag fine particles of 0.1 wt%, 1 wt%, 10 wt%, Inks containing 15 wt% (Ag average particle size 10 nm, protective colloid resin 5 wt%, aqueous dispersion) and black dye content 5 wt% (reactive dye: Reactive Black 31) And a light-shielding pattern was formed by overlapping with the same discharge amount using a thermal ink jet apparatus. Thereafter, the sample was dried at 80 ° C. for 1 hour, and the maximum density was measured with visible light beam diameters of 0.2 mmφ and 50 mmφ. The measurement results are shown in FIG. In the figure, A1 is a non-fired state with a light beam diameter of 0.2 mmφ, A2 is a fired state with a light beam diameter of 0.2 mmφ, B1 is a non-fired state with a light beam diameter of 50 mmφ, and B2 is a result of measurement after firing with a light beam diameter of 50 mmφ. is there. As shown in the results of FIG. 1, the ND values were 5.5 and 6.3 at the maximum, and excellent light shielding properties were obtained.

  On the same transparent substrate as in Example 1, an ink containing 25 wt% of Ag fine particles and a black dye content of 5 wt% is continuously changed from a thin concentration to an insulating coil concentration using a thermal ink jet apparatus. A light shielding pattern was formed. Then, it is dried at 80 ° C. for 1 hour and laminated with a protective film in which a 5 μm thick acrylic resin adhesive is uniformly applied to a 5 μm thick transparent PET film to obtain an ND filter having a continuous density gradient over a length of 120 mm. It was. The density gradient of the ND filter was measured with infrared light having a wavelength of 850 nm and a light flux of 2 mmφ. The measurement results are shown in FIG. As shown in the results of FIG. 2, it was found to have an excellent concentration gradient with an ND value of 0 to 4.6.

  On a PET transparent film having a thickness of 0.1 mm, an ink containing 40 wt% Ag fine particles and a black dye content of 1 wt% was applied by a gravure coater having a thickness of 5 μm. Thereafter, the film was dried at 80 ° C. for 1 hour, and the maximum density was measured with visible light beam diameters of 0.2 mmφ and 50 mmφ. As a result, excellent ND values of 4.5 and 5.6 were obtained.

Comparative Example 1

  On the same transparent substrate as in Example 1, 40 wt% Ag fine ink was applied and dried under the same conditions as in Example 1 using a thermal ink jet apparatus. When the maximum density was measured with visible light beam diameters of 0.2 mmφ and 50 mmφ, the maximum ND values were 2.5 and 3.1, and sufficient light-shielding properties could not be obtained with a coating layer containing only Ag fine particles.

Comparative Example 2

  On the same transparent substrate as in Example 1, an ink having a black dye content of 30 wt% was applied and dried under the same conditions as in Example 1 using a thermal ink jet apparatus. When the maximum density was measured at visible light beam diameters of 0.2 mmφ and 50 mmφ, the ND values were 1.3 and 1.7 at maximum, and sufficient light-shielding properties could not be obtained with a coating layer containing only black dye.

The graph which shows the light-shielding property of the ND filter formed in Example 1 of this invention The graph which shows the light-shielding property of the ND filter formed in Example 2 of this invention

Claims (9)

In an ND filter formed by forming an ink coating layer that absorbs light from a light source on a transparent substrate,
The coating layer of ink that absorbs light from the light source comprises a coating film of metal fine particle ink in which metal fine particles are dispersed and a coating film of dye ink that absorbs 90% or more of light from the light source. ND filter for high brightness light source. In an ND filter formed by forming a coating layer of ink that absorbs light from a light source on a transparent substrate,
The ink coating layer that absorbs light from the light source is a coating layer of a mixed ink of a metal fine particle ink and a dye ink having a single-layer coating film forming ability that absorbs light from the light source by 90% or more. An ND filter for a high-intensity light source.   The weight ratio of the metal fine particles and the other components including the dye in the ink coating layer that absorbs light from the light source is in a range of 100: 1 to 100. ND filter for high brightness light source.   The ND filter for a high-intensity light source according to any one of claims 1 to 3, wherein a transparent ink receiving layer is formed on a surface of the transparent substrate.   The ND filter for a high-intensity light source according to claim 4, wherein the ink receiving layer is composed of ultrafine inorganic particles and a resin binder, and pores having a pore diameter of 1 nm to 100 nm are formed on a surface thereof.   The metal fine particle ink is Au, Pt, Ag, Cu, Ni, Cr, Rh, Pd, Zn, Co, Mo, Ru, W, Os, Ir, Fe, Mn, Ge, 100 parts by weight of the dispersion medium. A dispersion prepared by containing 1 to 100 parts by weight of metal fine particles having a particle size of 1 nm to 100 nm selected from Sn, Ga, Al, Ti, V, Ta and In, The ND filter for a high-intensity light source according to any one of claims 2 to 5, wherein a protective colloid layer made of an organic substance is formed on the surface.   The ND filter for a high-intensity light source according to any one of claims 1 to 3, wherein the dye ink that absorbs 90% or more of light from the light source is a black dye ink.   The black dye ink is a direct dye, an acid dye, a basic dye, a disperse dye, a reactive dye, a mordant / acid mordant dye, an azoic dye, a sulfur / sulfur vat dye, a vat dye with respect to 100 parts by weight of a dispersion medium and a solvent. The ND filter for a high-intensity light source according to claim 7, wherein the ND filter is adjusted to contain 1 to 40 parts by weight of at least one dye.   The process of applying a coating layer of a metal fine particle ink, a black dye ink or a mixed ink of a metal fine particle ink and a black dye ink in a predetermined pattern on the surface of the transparent substrate is electrostatic coating. The method for producing an ND filter for a high-intensity light source according to any one of claims 1 to 8, wherein the method is performed by at least one coating method selected from printing, inkjet printing, and electrophotography.

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