Near infrared absorbing plate and optical filter including same

Abstract

To prevent visible light transmissivity and near-infrared light absorptivity from decreasing owing to interaction among a plurality of organic substances forming a light absorption layer.SOLUTION: There is provided a near-infrared absorption plate including: a glass plate 100; a first light absorption layer 200 which has a maximum absorption wavelength within a range of 850-1,200 nm; and a second light absorption layer 300 which is separate from the first light absorption layer and has a maximum absorption wavelength within a range of 650-750 nm, a haze being 0.3% or less.EFFECT: The near-infrared absorption plate can be made thin, and has superior mechanical properties such as strength or heat resistance etc.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present application relates to a near-infrared absorbing plate, an optical filter including the same, and an imaging device including the same. [Background technology]

[0002] Recently, with the widespread use of smartphones and tablet PCs, the demand for digital camera modules using image sensors is increasing. Digital camera modules used in mobile devices are developing in the direction of pursuing thinner designs and higher image quality. Video signals from digital cameras are acquired through image sensors. Unlike the human eye, image sensors made of semiconductors also react to light with wavelengths in the (near) infrared region. Therefore, in order to obtain image information similar to what the human eye sees, an infrared-ray cut filter (IRCF) that blocks light with wavelengths in the (near) infrared region is required.

[0003] As an example of IRCF, a reflective filter that reflects infrared rays and transmits only visible light wavelengths, manufactured by depositing a dielectric multilayer film on a glass substrate, has been considered. However, since reflective filters do not absorb near-infrared light wavelengths, they have a high internal reflection in the camera module. Internal reflection is the main cause of image ghosting (a phenomenon in which a developed image is perceived as blurry or an image that does not actually exist is perceived).

[0004] As another example of IRCF, ii) an inorganic absorption type filter (hereinafter also referred to as "blue filter") that absorbs and reflects near-infrared light has been considered, which is manufactured by depositing a dielectric multilayer film on a glass substrate (known as "blue glass") in which inorganic particles are dispersed and which shows a blue color. Blue filters are advantageous in suppressing the ghost phenomenon by absorbing near-infrared light. However, blue filters are very brittle and do not conform to the recent technological trend of thinning the total thickness of IRCF to 0.2 mm or less.

[0005] As another example of IRCF, iii) an organic absorption type filter that can absorb and reflect near infrared rays by applying a plurality of organic substances (light absorbing agents) having absorption maxima in different wavelength ranges to a transparent substrate and depositing a dielectric multilayer film has also been considered. Compared to inorganic absorption type filters, organic absorption type filters can control the wavelength of light that the filter can absorb relatively freely, and are therefore advantageous in increasing the absorption of light in the infrared region wavelength and decreasing the absorption of light in the visible region wavelength. In addition, organic absorption type filters have the advantage that there are no restrictions on the selection of a substrate (or board) and that a substrate with high strength can be freely selected because a light absorbing layer to which a light absorbing agent is applied is separately applied. However, organic absorption type filters have problems such as a decrease in visible light transmittance and a decrease in near infrared absorptance due to the interaction between the organic substances in the light absorbing layer.

[0006] For this reason, it is necessary to develop an infrared blocking filter that can prevent a decrease in visible light transmittance and near infrared light absorptance caused by interactions between the organic substances that make up the light absorbing layer. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Korean Patent Publication No. 10-2009-0051250 Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present application is to provide a near-infrared absorbing plate capable of preventing a decrease in visible light transmittance and (near) infrared absorptance caused by interactions between a plurality of organic substances that constitute a light absorbing layer. [Means for solving the problem]

[0009] The present application relates to near infrared absorbing plates (in particular, near infrared absorbing disks).

[0010] The near-infrared absorbing plate of the present application includes at least a glass substrate and a plurality of light absorbing layers having different optical properties. The plurality of light absorbing layers are present separately from each other.

[0011] The light absorbing layers are "separately present" in the above means that they are arranged so that there is no interaction between the light absorbing agents applied to each light absorbing layer. For example, when the near infrared absorbing plate of the present application includes a glass substrate, a first light absorbing layer, and a second light absorbing layer, and the light absorbing layers are separated from each other, it may mean that the absorbing plate has a laminated structure of the first light absorbing layer (second light absorbing layer) / glass substrate / second light absorbing layer (first light absorbing layer), or has a structure of the glass substrate / first light absorbing layer (second light absorbing layer) / second light absorbing layer (first light absorbing layer), so that there is no interaction or mixing between the light absorbing agents applied to the first and second light absorbing layers.

[0012] As described above, the multiple light absorbing layers applied to the near-infrared absorbing plate of the present application have different optical properties, or the existence forms of the components constituting each layer are different from each other. That is, the near-infrared absorbing plate of the present application includes at least a glass substrate, a first light absorbing layer, and a second light absorbing layer. The first light absorbing layer and the second light absorbing layer have different optical properties or the existence forms of the components constituting each layer. The first light absorbing layer and the second light absorbing layer are physically separated from each other and exist individually (or independently).

[0013] The first light absorbing layer and the second light absorbing layer applied to the near infrared absorbing plate of the present application have different optical properties. Specifically, the first light absorbing layer and the second light absorbing layer have different wavelength ranges having an absorption maximum. Specifically, the first light absorbing layer has an absorption maximum at a wavelength in the range of 850 nm to 1,200 nm, and the second light absorbing layer has an absorption maximum at a wavelength in the range of 650 nm to 750 nm. That is, the maximum absorption wavelength of the first light absorbing layer is in the range of 850 nm to 1,200 nm. The maximum absorption wavelength of the second light absorbing layer is in the range of 650 nm to 750 nm.

[0014] In the foregoing description, when a particular layer or component has an absorption maximum within a particular range of wavelengths, it means that it has a maximum absorption wavelength within that range of wavelengths, and when a layer or component has a maximum absorption wavelength within that range of wavelengths, it means that it has a minimum transmittance within that range of wavelengths.

[0015] In addition, the maximum absorption wavelength of the light absorbing layer may be measured for the light absorbing layer itself, or may be measured for a laminate composed of the light absorbing layer and a glass substrate. The maximum absorption wavelength of the light absorbing layer may be measured according to the method described in the examples described later.

[0016] In addition, the maximum absorption wavelength of the light absorbing layer can be adjusted by the composition of a light absorbing agent applied thereto or a composition for preparing the same, which will be described in detail later.

[0017] In the present application, a plurality of light absorbing layers having different maximum absorption wavelengths are included, and the light absorbing layers are configured to be present separately from each other, thereby preventing interactions between the light absorbing agents constituting each light absorbing layer, and as a result, the decrease in visible light transmittance and near infrared (or infrared) absorptance due to the interactions can be prevented. In addition, with the above-mentioned arrangement, the near infrared absorbing plate of the present application can have so-called optically transparent properties while preventing the decrease in physical properties due to the above-mentioned interactions between the light absorbing agents. Therefore, the near infrared absorbing plate of the present application can have a haze of 0.3% or less due to the above-mentioned arrangement.

[0018] For example, the haze of the near infrared absorbing plate may be 0.25% or less or 0.2% or less, and the lower limit is not particularly limited since the lower limit is better, and may be, for example, 0.001% or more, 0.01% or more, or 0.05% or more. As a measurement standard for the haze, a known measurement standard, such as ASTM D1003, may be applied. The reference wavelength for the haze may be, for example, 550 nm.

[0019] For example, the transmittance characteristic of the first light absorbing layer constituting the near infrared absorbing plate may be further controlled. Specifically, the first light absorbing layer may have a transmittance of 20% or less for light having any one wavelength within a wavelength range of 950 nm to 1,200 nm.

[0020] As another example, the reference wavelength of the transmittance of the first light absorption layer may be 960 nm or more, 970 nm or more, 980 nm or more, 990 nm or more, or 1,000 nm or more, and may be 1,190 nm or less, 1,180 nm or less, 1,170 nm or less, 1,160 nm or less, 1,150 nm or less, 1,140 nm or less, 1,130 nm or less, 1,120 nm or less, 1,110 nm or less, 1,100 nm or less, 1,090 nm or less, 1,080 nm or less, 1,070 nm or less, 1,060 nm or less, or 1,050 nm or less.

[0021] The transmittance of the first light absorbing layer may be, for example, 19% or less, 18% or less, 17% or less, 16% or less, or 15% or less, and the lower limit is not particularly limited since the lower limit means that the absorbance is higher, but may be 0.01% or more, 0.1% or more, 1% or more, 5% or more, or 10% or more. The manner in which such transmittance can be achieved will be described later.

[0022] For example, the transmittance characteristic of the second light absorbing layer constituting the near infrared absorbing plate may be further controlled. Specifically, the second light absorbing layer may have a transmittance of 5% or less for light having any one of wavelengths in the range of 670 nm to 730 nm.

[0023] As another example, the reference wavelength of the transmittance of the second light absorbing layer may be 675 nm or more, 680 nm or more, 685 nm or more, 690 nm or more, or 695 nm or more, and may be 725 nm or less, 720 nm or less, 715 nm or less, 710 nm or less, 705 nm or less, or 700 nm or less.

[0024] The transmittance of the second light absorbing layer may, for example, be 4.5% or less, 3% or less, 3.5% or less, 3% or less, 2.5% or less, or 2% or less. The lower limit is not particularly limited since a lower limit means a higher absorptance, but may be 0.01% or more, 0.1% or more, 0.5% or more, or 1% or more.

[0025] The near-infrared absorbing plate of the present application includes at least a plurality of light absorbing layers (first and second light absorbing layers) that satisfy the above-mentioned characteristics, and thus can exhibit unique optical characteristics, for example, a specific transmittance.

[0026] For example, the near infrared ray absorbing plate may have a transmittance of 60% or more for light having a wavelength of 450 nm. For another example, the transmittance of the near infrared ray absorbing plate may be 65% or more or 70% or more for light having a wavelength of 450 nm. The upper limit of the transmittance is not particularly limited because the higher the transmittance, the more advantageous it is, but may be about 100%, 95% or less, 90% or less, 85% or less, or 80% or less.

[0027] For example, the near infrared absorbing plate may have a transmittance of 70% or more for light with a wavelength of 550 nm. For another example, the transmittance of the near infrared absorbing plate may be 75% or more or 80% or more for light with a wavelength of 550 nm. The upper limit of the transmittance is not particularly limited because the higher the transmittance, the more advantageous it is, but may be about 100%, 95% or less, or 90% or less.

[0028] For example, the near infrared absorbing plate may have a transmittance of 40% or less for light with a wavelength of 1,050 nm. The transmittance of the light with a wavelength of 1,050 nm may be, for example, 37% or less, 35% or less, 33% or less, or 30% or less, and the lower limit is not particularly limited since the lower the better, but may be 1% or more, 5% or more, 10% or more, 15% or more, or 20% or more.

[0029] The light transmittance and the like of the near-infrared absorbing plate may be values ​​measured using a known spectrophotometer for the near-infrared absorbing plate.

[0030] From the viewpoint of ensuring appropriate mechanical properties such as strength, the near infrared absorbing plate of the present application includes a glass substrate as a base material supporting the first light absorbing layer and the second light absorbing layer.

[0031] In the near infrared absorbing plate of the present application, a glass substrate having a particularly high strength, for example, a tempered glass substrate, can be applied as the glass substrate from the viewpoint of improving the mechanical properties of the plate. Specifically, the glass substrate applied to the near infrared absorbing plate of the present application may have a three-point bending strength measured according to the ASTM D790 standard of 360 MPa or more. As another example, the three-point bending strength may be 370 MPa or more, 380 MPa or more, 390 MPa or more, 400 MPa or more, 410 MPa or more, 420 MPa or more, 430 MPa or more, 440 MPa or more, 450 MPa or more, 460 MPa or more, 470 MPa or more, 480 MPa or more, 490 MPa or more, or 500 MPa or more.

[0032] In the present application, the type of glass substrate applicable to the tempered glass substrate is not particularly limited as long as it satisfies the above-mentioned bending strength. For example, physically tempered glass or chemically tempered glass can be applied, and preferably, chemically tempered glass can be applied.

[0033] As an example, the tempered glass substrate may include a first compressive stress layer present on a first main surface of the glass substrate and a second compressive stress layer present on a second main surface opposite to the first main surface. By applying a glass substrate (chemically) tempered through a compressive stress layer in this manner, the near-infrared absorbing plate of the present application may have improved strength. In addition, an imaging device to which such a near-infrared absorbing plate or an optical filter having the near-infrared absorbing plate is applied may ensure high weather resistance.

[0034] The method of forming the compressive stress layer on the glass substrate is not particularly limited, and a known physical or chemical strengthening method for glass substrates may be applied. However, in order to minimize damage to the glass substrate, the compressive stress layer may be formed by a chemical strengthening method. The compressive stress layer may be formed by a Na + In the conventional glass substrate containing ions, the Na + Ion is K + It can mean a site substituted with an ion. + Ion is K + In the process of being replaced by ions, K + The layer up to the site where the ions are replaced is defined as a compressive stress layer. In general, the compressive stress layer is known as a DOL (Depth of compressive stress layer). That is, the compressive stress layer is formed toward the inside of the glass substrate, since the components in the glass substrate are replaced with other components by an external treatment (such as heat treatment) (this point is the same as the meaning of calling the compressive stress layer DOL).

[0035] In the near-infrared absorbing plate of the present application, the thickness of each of the first compressive stress layer and the second compressive stress layer included in the strengthened glass substrate may be approximately 30% or less of the total thickness of the near-infrared absorbing plate. Specifically, the thickness of each of the first compressive stress layer and the second compressive stress layer may be in the range of 1 μm or more and 30 μm or less. As another example, the thickness may be 5 μm or more, 10 μm or more, or 15 μm or more, and 25 μm or less, or 20 μm or less. The near-infrared absorbing plate of the present application may be a thin near-infrared absorbing plate having excellent strength by applying a strengthened glass substrate including a compressive stress layer formed with a thickness within the above range.

[0036] When the thickness of the compressive stress layer is not constant, the thickness of the compressive stress layer may refer to the maximum thickness, the minimum thickness, or the average thickness of the maximum thickness and the minimum thickness of the compressive stress layer.

[0037] In the near infrared absorbing plate of the present application, the thickness of the glass substrate may be appropriately adjusted in order to ensure appropriate mechanical and physical properties. For example, the thickness of the glass substrate may be in the range of 0.07 mm to 0.3 mm. As described above, the thickness may refer to the maximum thickness, the minimum thickness, or the average thickness of the maximum thickness and the minimum thickness of the glass substrate. As another example, the thickness of the glass substrate may be in the range of 0.07 mm to 0.02 mm.

[0038] As described above, in the near-infrared absorbing plate of the present application, from the viewpoint of ensuring appropriate optical properties (e.g., improved transmittance for light in the visible light region and improved absorptance for light in the near-infrared region), the first light absorbing layer and the second light absorbing layer are configured as layers independent of each other.

[0039] As described above, the first light absorbing layer and the second light absorbing layer being independent of each other or being configured separately can mean, for example, that the first light absorbing layer and the second light absorbing layer are configured so that they are not in physical contact with each other or no mixing occurs between their components.

[0040] As described above, there are various known methods for disposing the first light absorbing layer and the second light absorbing layer so that they are present separately. For example, in the near-infrared absorbing plate of the present application, the first light absorbing layer may be disposed on one surface of the glass substrate, and the second light absorbing layer may be disposed on the other surface of the glass substrate, so that the first light absorbing layer and the second light absorbing layer are disposed so that they are present separately. That is, in the near-infrared absorbing plate of the present application, the first light absorbing layer may be disposed on one surface of the glass substrate, and the second light absorbing layer may be disposed on the other surface of the glass substrate. In other words, in the near-infrared absorbing plate, the first light absorbing layer may be disposed on the opposite side of the second light absorbing layer with respect to the glass substrate.

[0041] As another example, the first and second light absorbing layers may be laminated in order on one surface of a glass substrate, and may be separated from each other as described above. In this case, the near infrared absorbing plate may have a structure in which the glass substrate, the first light absorbing layer, and the second light absorbing layer are present in the above order, or the glass substrate, the second light absorbing layer, and the first light absorbing layer are present in the above order.

[0042] Such a laminated structure is shown in Figures 1 and 2. The near-infrared absorbing plate of the present application may have a structure in which the first light absorbing layer 200, the glass substrate 100, and the second light absorbing layer 300 are present in the above order (see Figure 1), or may have a structure in which the second light absorbing layer 300, the glass substrate 100, and the first light absorbing layer 200 are present in the above order (see Figure 2).

[0043] In addition, the near-infrared absorbing plate of the present application may have a structure in which the first light absorbing layer and the second light absorbing layer are laminated on one surface of the glass substrate, as described above. The near-infrared absorbing plate may have a structure in which, for example, the glass substrate 100, the first light absorbing layer 200, and the second light absorbing layer 300 are present in the above order (see FIG. 3), or may have a structure in which the glass substrate 100, the second light absorbing layer 300, and the first light absorbing layer 200 are present in the above order (not shown). The near-infrared absorbing plate preferably has a structure including the glass substrate 100, the first light absorbing layer 200, and the second light absorbing layer 300 in the above order.

[0044] As described later, when the first light absorbing layer and the second light absorbing layer have a structure adjacent to each other (a laminated structure of glass substrate / second light absorbing layer / first light absorbing layer or glass substrate / first light absorbing layer / second light absorbing layer), the first light absorbing layer and the second light absorbing layer must be clearly separated from each other so that the light absorbing agent (or dye) applied to each light absorbing layer does not mix. This is because the optical properties may be deteriorated due to the mixing of the dyes applied to the first and second light absorbing layers. As one of such methods, the first light absorbing layer and the second light absorbing layer may be separated from each other by introducing a separation layer 400 between the first light absorbing layer 200 and the second light absorbing layer 300 (see FIG. 4).

[0045] The separation layer may be a known functional layer that functions to prevent mixing between the components of the first light absorbing layer and the components of the second light absorbing layer (e.g., light absorbing agents such as dyes, etc.) For example, a known barrier film or the like may be applied as the separation layer, and as another example, a known adhesive may be applied.

[0046] From the viewpoint of securing the optical properties targeted by the near-infrared absorbing plate of the present application and securing appropriate adhesion between the light absorbing layers, it may be advantageous to apply an adhesive layer (or adhesive layer) as the separation layer. The term "adhesion" as used herein may refer to the phenomenon in which two substances come into contact and are bonded by physical and / or chemical bonding forces, and "adhesive" may refer to a known chemical material provided so that the adhesive and the surface of the adherend are bonded by the bonding force at the interface.

[0047] The adhesive layer may be generally formed by curing or crosslinking an adhesive composition containing an adhesive resin or the like. In this case, the type of resin that may form the adhesive layer (adhesive layer) is not particularly limited. As the resin, any resin freely selected from known adhesive resins may be applied as long as it can ensure an appropriate adhesive force between the first light absorbing layer and the second light absorbing layer. Examples of the resin applied to the adhesive layer include one or more of cyclic olefin resins, polyacrylate resins, polyisocyanate resins, polyimide resins, polyetherimide resins, polyamideimide resins, acrylic resins, polycarbonate resins, and polyethylene naphthalate resins.

[0048] In the above description, the thickness of the separation layer (adhesive layer or adhesive layer) can be appropriately adjusted in order to prevent interaction (or mixing) between the dyes constituting the first light absorbing layer and the second light absorbing layer and to configure the near-infrared absorbing plate to exhibit optically transparent properties. The thickness of the separation layer can be 0.2 μm or more. As another example, the thickness can be 0.3 μm or more, 0.4 μm or more, or 0.5 μm or more, and the upper limit is not particularly limited and can be appropriately adjusted within a limit that does not significantly affect the intended final thickness of the near-infrared absorbing plate.

[0049] The thickness of the adhesive layer can be determined by the application of the adhesive composition capable of forming the adhesive layer, specifically, the coating method. For example, when a spin coating method is adopted as the coating method of the adhesive composition, the thickness of the adhesive layer can be reduced as the rotation speed of the spin coater increases within the same coating time.

[0050] The thickness of each of the light absorbing layers is not particularly limited. The thickness of each of the light absorbing layers can be appropriately adjusted within a range in which the average thickness of the near infrared absorbing plate described later can be formed. The thickness of each of the first light absorbing layer and the second light absorbing layer can be, for example, in the range of 0.25 μm to 10 μm. As another example, the thickness can be 0.5 μm or more and 5 μm or less. The thickness of each of the first light absorbing layer and the second light absorbing layer can be the same or different from each other.

[0051] In this application, when the thickness of any member is not constant, the thickness may refer to the maximum thickness, the minimum thickness, or the average thickness of said maximum and minimum thicknesses of that member.

[0052] The near-infrared absorbing plate of the present application can have a small thickness by applying the glass substrate, the first and second light absorbing layers. Specifically, the thickness of the near-infrared absorbing plate can be, for example, 0.3 mm or less, 0.23 mm or less, or 0.22 mm or less. As another example, the thickness can be in the range of 0.08 mm or more and 0.15 mm or less. As described above, when the thickness of the near-infrared absorbing plate is not constant, the thickness can be the maximum thickness, the minimum thickness, or the average thickness of the maximum thickness and the minimum thickness.

[0053] In the near-infrared absorbing plate of the present application, each of the first and second light absorbing layers may contain a dye (a first dye and a second dye, respectively) so as to exhibit the optical properties such as the transmittance described above, and the optical properties of the light absorbing layer described above can be adjusted by adjusting the optical properties of the first and second dyes applied thereto. That is, as the first dye and the second dye applied to the first light absorbing layer and the second light absorbing layer, respectively, dyes having different optical properties, specifically, dyes having maximum absorption wavelengths within different ranges, may be applied.

[0054] Specifically, the maximum absorption wavelength of the first dye applied to the first light absorbing layer may be in the range of 850 nm to 1,200 nm. Also, the maximum absorption wavelength of the second dye applied to the second light absorbing layer may be in the range of 650 nm to 750 nm. That is, the first light absorbing layer and the second light absorbing layer of the near infrared absorbing plate may have different optical properties. As described above, when a plurality of dyes having different optical properties are applied to one light absorbing layer, the visible light transmittance and / or near infrared (or infrared) absorptance may be reduced due to the interaction between the dyes. However, in the present application, the dyes having different optical properties are applied to different layers so that they can exist independently, thereby ensuring improved optical properties.

[0055] The maximum absorption wavelengths of the first and second dyes may be the same as the maximum absorption wavelengths of the first and second light absorbing layers, or may be different from each other. The maximum absorption wavelengths of the first and second dyes may be the maximum absorption wavelengths measured for the first and second dyes themselves, may be the maximum absorption wavelengths measured for a solution in which the first or second dye is mixed with a solvent, may be the maximum absorption wavelengths of a light absorbing layer made of a binder resin appropriately mixed with the dyes, or may be the maximum absorption wavelengths measured for a laminate made of the light absorbing layer and a known glass substrate.

[0056] The first and second dyes may be present in the first and second light absorbing layers in a state of being blended with a first binder resin and a second binder resin, respectively. In this case, the first and second dyes may be configured in the first and second light absorbing layers in such a way that their existence forms with the first and second binder resins are different from each other.

[0057] As an example, the first light absorbing layer may include a first binder resin and a first dye dispersed in the first binder resin. That is, the first dye is not dissolved in other components (e.g., the binder resin or a solvent described below) in the first light absorbing layer, and specifically, may be present in a form dispersed in a matrix formed by the first binder resin. Specifically, the first dye may be present in the form of independent particles in the first light absorbing layer.

[0058] The method of designing the specific dye to exist in the light absorbing layer in a dispersed form is not particularly limited. For example, in the present application, the composition of the raw material or the composition for forming the light absorbing layer for forming the first light absorbing layer can be adjusted to a specific composition. Specifically, in the present application, the composition for forming the light absorbing layer containing the first dye, the first binder resin, and the solvent (first solvent) can be cured to manufacture the first light absorbing layer. That is, the first light absorbing layer can be a cured product of the composition for forming the light absorbing layer containing the first dye, the first binder resin, and the first solvent. In this case, a solvent showing a specific solubility for the first dye and the first binder resin can be applied as the solvent (first solvent) so that the first dye can exist in the first light absorbing layer in a dispersed form in the first binder resin. Specifically, the first solvent can be selected to have a solubility of the first dye in the first solvent of 15 g / L or less.

[0059] In the above description, solubility may mean the ratio (g / L) of the mass (g) of the solute dissolved per unit volume (L) of the solvent. As another example, the solubility of the first dye in the first solvent may be 0 g / L or more and 15 g / L or less. In the above, the solubility of 0 g / L may mean that the solute is completely insoluble in the solvent.

[0060] The solubility may be a value measured at room temperature. The term "room temperature" may refer to a natural temperature that is not particularly heated or cooled, specifically, any temperature within a range of 15°C to 30°C, any temperature within a range of 20°C to 25°C, or about 23°C.

[0061] In this way, the first light absorbing layer and the second light absorbing layer having different optical properties are separated and the first dye is present in the first light absorbing layer in a dispersed form. However, by appropriately selecting a specific solvent in the composition forming the first light absorbing layer such that the solubility of the first dye becomes the above-mentioned value, the light transmittance of the first light absorbing layer in the visible light region (for example, a wavelength region in the range of 450 nm to 600 nm) can be increased, and the near-infrared absorbing plate including the light absorbing layer can have a high transmittance in the visible light region while at the same time having a high light absorptance (or light blocking rate) in the infrared region (or near-infrared, a wavelength region in the range of 700 nm to 1,200 nm).

[0062] In order to configure the first light absorbing layer so that the first dye is present in a dispersed state in the first binder resin, a solvent having the above-mentioned solubility for the first dye and a solvent having a solubility of about 100 g / L or more for the first binder resin can be applied. That is, as a composition applied to form the first light absorbing layer, a solvent that dissolves the first dye having the above-mentioned optical characteristics (maximum absorption wavelength) but does not dissolve the first binder resin applied thereto can be applied.

[0063] As described above, the second light absorbing layer applied to the near infrared absorbing plate of the present application has physical properties and / or composition that are different from those of the first light absorbing layer. Therefore, the second light absorbing layer may contain at least a dye (second dye) different from the dye applied to the first light absorbing layer. Also, the second light absorbing layer may further contain a second binder resin in addition to the second dye. In this case, the second dye in the second light absorbing layer may exist in a dissolved state, unlike the first dye in the first light absorbing layer. Specifically, the second dye may be dissolved in a solvent (second solvent) applied in the process of manufacturing the second light absorbing layer, or may exist in a state of coloring the binder resin (second binder resin) applied thereto.

[0064] In the above description, the composition for forming the second light absorbing layer may also contain the second dye, a binder resin (second binder resin) and a solvent (second solvent) like the composition for forming the first light absorbing layer. In addition, the second solvent may be selected to have a specific solubility for the second dye so that the second dye can exhibit the above-mentioned existence state in the second light absorbing layer. Specifically, the second dye may be present in a dissolved state in the second light absorbing layer, and it may be advantageous for the second dye to have a solubility in the second solvent that exceeds a specific value. For example, the second dye may have a solubility in the second solvent that exceeds 15 g / L. The solubility of the second dye in the second solvent may, for example, be 20 g / L or more, 30 g / L or more, 40 g / L or more, 50 g / L or more, 60 g / L or more, 70 g / L or more, 80 g / L or more, 90 g / L or more, or 100 g / L or more, and the upper limit is not particularly limited and is appropriate as long as the second dye can be sufficiently dissolved.

[0065] The first solvent or the second solvent applied in the process of forming the first light absorbing layer or the second light absorbing layer can be freely selected from known solvents, specifically known organic solvents, as long as it can satisfy the solubility of the first dye or the second dye, respectively. Specifically, the first light absorbing layer forming composition or the second light absorbing layer forming composition can respectively use methyl isobutyl ketone, propylene glycol methyl ether acetate or diethylene glycol monoethyl ether 3-methoxybutanol, ethylene glycol monobutyl ether acetate, 4-hydroxy-4-methyl-2-pentanone, γ-butyrolactone, cyclohexanone, toluene, pyridone, etc. as the first solvent or the second solvent.

[0066] In the above description, the binder resin may mean a component applied to impart fixing power between components constituting the light absorbing layer. On the other hand, from the viewpoint of ensuring excellent optical properties of the near infrared absorbing plate, it is appropriate to apply an optically transparent resin as the binder.

[0067] "Optically transparent" can mean that the transmittance for visible light, for example light with a wavelength of 550 nm, is 90% or more, 95% or more, 99% or more, or about 100%.

[0068] In addition, the first binder resin or the second binder resin applied in the process of forming the first light absorbing layer or the second light absorbing layer may be freely selected from known binder resins as long as it can exhibit the above-mentioned characteristics together with the first dye and the first solvent or the second dye and the second solvent.

[0069] The binder resin may be, for example, one or more of a cyclic olefin resin, a polyarylate resin, a polyisocyanate resin, a polyimide resin, a polyetherimide resin, a polyamideimide resin, an acrylic resin, a polycarbonate resin, and a polyethylene naphthalate resin. In the present application, the first binder resin and the second binder resin may be the same or different from each other.

[0070] The method of forming the light absorbing layer in the near infrared absorbing plate of the present application is not particularly limited. For example, the first light absorbing layer and the second light absorbing layer of the near infrared absorbing plate can be prepared by curing a composition for forming a light absorbing layer, specifically a composition including the dye, binder resin and solvent described above. The curing method is not particularly limited, and a known curing method, for example, heat curing, light curing, or a dual curing method of heat and light, can be applied.

[0071] The near infrared absorbing plate of the present application may be manufactured by preparing each of the compositions for forming the first light absorbing layer and the composition for forming the second light absorbing layer, coating any one of the compositions on a substrate (the above-mentioned glass substrate or tempered glass substrate) and curing the composition, and then coating the remaining one of the compositions on the cured layer or another surface of the glass substrate and curing the composition.

[0072] As described above, the first and second light absorbing layers may be manufactured by applying (or coating) compositions required for forming each layer and then curing the applied compositions, and generally, since the solvent evaporates during the curing process, the first light absorbing layer may include a first dye and a first binder resin, and the second light absorbing layer may include a second dye and a second binder resin. In this case, since the first solvent applied during the manufacturing process of the first light absorbing layer does not dissolve the first dye to a specific value or more, the first dye is contained in the form of particles in the composition, and therefore, in the first light absorbing layer, the first dye may be present dispersed in the first binder resin, specifically, in a resin matrix formed by the first binder resin.

[0073] For the same reason, the second light absorbing layer may contain a second binder resin and a second dye, and in this case, the second solvent applied in the manufacturing process of the second light absorbing layer has high solubility for the second dye, so that the second dye can be dissolved by the solvent in the composition for forming the second light absorbing layer. However, since the solvent volatilizes in the manufacturing (curing) process, the second light absorbing layer may contain the second binder resin and the second dye, and the second dye may exist in a state in which it colors the second binder resin.

[0074] As an example, the ratio of the first dye and the second dye is not particularly limited. For example, the ratio of the first dye and the second dye may be in the range of 0.01 to 10 parts by weight, 0.01 to 8 parts by weight, or 0.01 to 5 parts by weight based on 100 parts by weight of the binder resin when the binder resin is applied to the composition forming the light absorbing layer. The ratio of the first dye and the second dye may be the ratio in each of the first light absorbing layer and the second light absorbing layer, and may mean the ratio in each of the composition for forming the first light absorbing layer and the composition for forming the second light absorbing layer.

[0075] As an example, in order to make the first light absorbing layer and / or the second light absorbing layer have a further maximum absorption wavelength other than the above-mentioned maximum absorption wavelength, the first light absorbing layer and / or the second light absorbing layer may further contain a dye (third dye) different from the first dye and / or the second dye. In this case, the ratio of the third dye may be in the range of 0.01 parts by weight to 5 parts by weight with respect to 100 parts by weight of the composition forming the light absorbing layer or the binder resin applied thereto in the light absorbing layer. When one type of dye is applied as the third dye, the ratio may mean the ratio of that one type, and when multiple dyes are used in combination, the ratio may mean the ratio of each of the dyes.

[0076] In this case, the type of the third dye is not particularly limited. As the third dye, one or more of dyes, pigments, or metal complex compounds having a maximum absorption wavelength in the ultraviolet region or infrared (or near infrared) region can be applied. Specifically, the further third dye includes indoles, oxazoles, merocyanines, cyanines, naphthalimides, oxadiazoles, oxazines, oxalidines, naphthalic acids, styryls, anthracenes, cyclic carbonyls, triazoles, phthalocyanines, naphthalocyanines, porphyrins, benzoporphyrins, squaryliums, anthraquinones, croconiums, dithiol metal complexes, and the like. The third dye may be applied alone to the first light absorbing layer or the second light absorbing layer, or in some cases, two or more of the dyes listed above may be mixed and applied.

[0077] The type of the first dye is not particularly limited as long as it has the above-mentioned optical properties, for example, the above-mentioned maximum absorption wavelength. As the first dye, for example, a cyanine compound, a phthalocyanine compound, a naphthalocyanine compound, a porphyrin compound, a benzoporphyrin compound, a diimonium compound, a squarylium compound, an anthraquinone compound, a croconium compound, or a dithiol metal complex compound can be used.

[0078] On the other hand, in view of the relationship with the maximum absorption wavelength of the first light absorbing layer and making the second light absorbing layer have a maximum absorption wavelength within the above-mentioned range, it may be advantageous to use a diimonium compound as the first dye.

[0079] The diimonium-based compound may be represented, for example, by a compound of the following formula 1. Accordingly, the first dye may include the compound of formula 1.

[0080] [ka]

[0081] In the formula 1, R1 to R8 are each independently a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, an alkenyl group, or an alkynyl group, R9 to R11 are each independently a hydrogen atom, a halogen group, an amino group, a cyano group, a nitro group, a carboxy group, an alkyl group, or an alkoxy group, and X- is an anion. - , I - , F - , ClO4 - , BF4 - , SbF6 - , CF3SO3 - or CH3C6H4SO3 - etc.

[0082] In this application, the term "alkyl group" may mean a substituent derived from a straight-chain or branched-chain saturated hydrocarbon.Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, a 1,1-dimethylpropyl group, a 1,2-dimethylpropyl group, a 2,2-dimethylpropyl group, a 1-ethylpropyl group, a 2-ethylpropyl group, an n-hexyl group, a 1-methyl-2-ethylpropyl group, a 1-ethyl-2-methylpropyl group, a 1,1,2-trimethylpropyl group, and a 1,1,2-trimethylpropyl group. Examples of the alkyl group include 1-propylpropyl group, 1-methylbutyl group, 2-methylbutyl group, 1,1-dimethylbutyl group, 1,2-dimethylbutyl group, 2,2-dimethylbutyl group, 1,3-dimethylbutyl group, 2,3-dimethylbutyl group, 2-ethylbutyl group, 2-methylpentyl group, and 3-methylpentyl group. The alkyl group may be an alkyl group having 1 to 20, 1 to 12, 1 to 6, or 1 to 4 carbon atoms.

[0083] In the present application, the term "cycloalkyl group" may refer to a substituent derived from a monocyclic saturated hydrocarbon. Examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group. The cycloalkyl group may refer to a cycloalkyl group having 3 to 20, 3 to 12, 3 to 9, or 3 to 6 carbon atoms.

[0084] In this application, the term "aryl group" means a monovalent substituent derived from an aromatic hydrocarbon. Examples of the aryl group include a phenyl group, a naphthyl group, an anthracenyl group, a phenanthryl group, a naphthacenyl group, a pyrenyl group, a tolyl group, a biphenyl group, a terphenyl group, a chrycenyl group, a spirobifluorenyl group, a fluoranthenyl group, a fluorenyl group, a perylenyl group, an indenyl group, an azulenyl group, a heptalenyl group, a phenalenyl group, and a phenanthrenyl group. The aryl group may be an aryl group having 6 to 30, 6 to 24, 6 to 18, or 6 to 12 carbon atoms.

[0085] In the present application, the term "aralkyl group" may refer to a monovalent substituent derived from a saturated hydrocarbon compound in which a monovalent substituent derived from an aromatic hydrocarbon is bonded to a hydrogen site of a terminal hydrocarbon. That is, the aralkyl group refers to an alkyl group whose chain end is substituted with an aryl group. Examples of the aralkyl group include a benzyl group, a methylbenzyl group, a phenethyl group, a phenylpropyl group, a naphthalenylmethyl group, and a naphthalenylethyl group.

[0086] As an example, the type of the second dye is not particularly limited as long as it has the above-mentioned optical characteristics, for example, the maximum absorption wavelength of the second light absorbing layer or the second dye itself. For example, the second dye may be a compound that is included in the category of the first dye and satisfies the above-mentioned optical characteristics, but is different from the first dye.

[0087] Meanwhile, from the viewpoint of making the second dye itself or the second light absorbing layer have the maximum absorption wavelength, a dye containing a squarylium-based compound can be applied as the second dye. The squarylium-based compound can be a compound represented by the following Chemical Formula 2. That is, the second dye can include a compound represented by the following Chemical Formula 2.

[0088] [ka]

[0089] TIFF0007662176000003.tif82170

[0090] In addition, in Formula 2, when at least one of hydrogen atoms present in the aminophenyl group, the indolylmethylene group, the indolinyl group, or the pyrimidine group is independently an aryl group, the aryl group may be further substituted with an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms.

[0091] The compound of Formula 2 may be any one of the compounds of Formulas 2a to 2d below:

[0092] [ka]

[0093] [ka]

[0094] [ka]

[0095] [ka]

[0096] In the above Chemical Formulae 2a to 2d, a1, a2, a3, and a4 are each independently a hydrogen atom, a halogen atom, a hydroxyl group, a cyano group, a nitro group, a carboxyl group, an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an aralkyl group having 7 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, a sulfonamide group, or an amide group substituted or unsubstituted with an alkyl group having 1 to 4 carbon atoms, a haloalkyl group having 1 to 4 carbon atoms, or an aralkyl group having 7 to 20 carbon atoms. As another example, in the above Chemical Formulae 2a to 2d, when a1, a2, a3, and a4 are each independently an aryl group having 6 to 20 carbon atoms, one or more hydrogen atoms of the aryl group may be further substituted with an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms.

[0097] The present application also relates to an optical filter including the near-infrared absorbing plate. Specifically, the optical filter of the present application may be a near-infrared (or infrared) blocking filter.

[0098] The optical filter includes the near infrared absorbing plate and a selective wavelength reflecting layer present on one or both sides of the near infrared absorbing plate. The term "selective wavelength reflecting layer" may refer to a functional optical member or layer formed to reflect light of a specific wavelength and transmit light of a wavelength different from the reflected light without reflecting it.

[0099] Specifically, the selective wavelength reflective layer applied to the optical filter of the present application may refer to a functional layer designed to reflect light having a wavelength of 650 nm or more, for example, a wavelength in the range of 700 nm to 1,200 nm, among light incident on the optical filter, thereby blocking light within the above wavelength range from passing through the optical filter, and / or to prevent light having a wavelength in the range of 400 nm to 650 nm from being reflected, i.e., to transmit light within the above wavelength range. That is, the selective wavelength reflective layer may function as a near-infrared reflective layer that reflects near-infrared rays and / or a visible light anti-reflection layer that prevents visible light from being reflected.

[0100] The selective wavelength reflective layer may include a dielectric multilayer film, that is, the optical filter of the present application may be formed by forming a dielectric multilayer film on one or both sides of the near infrared absorbing plate.

[0101] As an example, the dielectric multilayer film may have a structure in which dielectric films having different refractive indices are alternately formed. For example, the dielectric multilayer film may be formed by repeating a low refractive index-high refractive index-low refractive index dielectric film in this order, or a high refractive index-low refractive index-high refractive index dielectric film in this order. The deviation in refractive index between the high refractive index dielectric film and the low refractive index dielectric film may be 0.2 or more, 0.3 or more, 0.4 or more, or 0.5 or more, and may be 1.5 or less, or 1.0 or less. The reference wavelength of the refractive index may be 550 nm.

[0102] In the above description, the refractive index of the low refractive index dielectric film may be in the range of 1.4 to 1.6. Low refractive index dielectric films having such a refractive index may include silicon dioxide, lanthanum fluoride, magnesium fluoride, sodium aluminum hexafluoride, etc. The reference wavelength of the refractive index may be 550 nm.

[0103] In the above description, the refractive index of the high refractive index dielectric film may be in the range of 2.1 to 2.5. The high refractive index dielectric film having such a refractive index may include titanium dioxide, aluminum oxide, zirconium oxide, tantalum pentoxide, niobium pentoxide, lanthanum oxide, yttrium oxide, zinc oxide, zinc sulfide, indium oxide, etc., and the indium oxide may include titanium dioxide, tin oxide, cerium oxide, etc. The reference wavelength of the refractive index may be 550 nm.

[0104] As another example, in the optical filter, the high refractive index dielectric film and the low refractive index dielectric film may be formed separately from each other. As an example, a high refractive index dielectric film or a low refractive index dielectric film may be present on one surface of the near infrared absorbing plate, and a low refractive index dielectric film or a high refractive index dielectric film may be present on the other surface. As another example, a high refractive index dielectric film and a low refractive index dielectric film may be present on one surface of the near infrared absorbing plate in the above order or in the reverse order, and the above-mentioned separation layer may be present between the high refractive index dielectric film and the low refractive index dielectric film.

[0105] In another embodiment, the present application relates to an imaging device, the imaging device including the optical filter (specifically, a near-infrared blocking filter or the like) or the near-infrared absorbing plate.

[0106] The imaging device may include any known essential components for forming its function. For example, the imaging device may further include a lens and an image sensor in addition to the optical device or the near-infrared absorbing plate. Effect of the Invention

[0107] The near-infrared absorbing plate of the present application can prevent a decrease in visible light transmittance and near-infrared absorptance caused by interactions between a plurality of organic substances that constitute the light absorbing layer.

[0108] The near-infrared absorbing plate of the present application also has the advantage that it can be made thin.

[0109] The near infrared absorbing plate of the present application also has the advantage of being excellent in mechanical properties such as strength and heat resistance. [Brief description of the drawings]

[0110] [Figure 1] 1 shows a layered structure of a near-infrared absorbing plate according to an embodiment of the present application. [Diagram 2] 1 shows a layered structure of a near-infrared absorbing plate according to an embodiment of the present application. [Diagram 3] 1 shows a layered structure of a near-infrared absorbing plate according to an embodiment of the present application. [Figure 4] 1 shows a layered structure of a near-infrared absorbing plate according to an embodiment of the present application. [Diagram 5] 1 shows transmittance spectra of Production Examples 1 to 3 of the present application. [Figure 6] 1 shows transmittance spectra of Production Examples 4 and 5. [Figure 7] 1 shows transmittance spectra of Production Examples 6 to 11. [Figure 8]1 shows transmittance spectra of Production Examples 12 to 14. [Figure 9] 1 shows transmittance spectra of Production Examples 15 to 20. [Figure 10] 1 shows transmittance spectra of Examples 1-2 and Comparative Examples 1-3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0111] The present application will be described in detail below with reference to examples and comparative examples. However, the scope of the present application is not limited to the following examples and comparative examples.

[0112] [Light transmittance measurement] The transmittance of each wavelength of the results of the Preparation Examples, Examples, and Comparative Examples was measured using a spectrophotometer (Perkin Elmer, Lambda 750 product) according to the manual of the device.

[0113] [Haze] The haze of the results of the examples and comparative examples was measured for light with a wavelength of 550 nm using a haze meter (Nippon Denshoku Co., Ltd., NDH-200N product) according to the JIS K 7136 test method in accordance with the equipment manual.

[0114] [Manufacturing of tempered glass substrates] A tempered glass substrate was produced by the following method.

[0115] i) Aluminosilicate glass (AS-87 product by Schott) is washed with an alkaline aqueous solution to prepare a glass substrate having a thickness of approximately 0.1 mm.

[0116] ii) The glass substrate is immersed in a potassium nitrate solution and heat-treated in the solution at a temperature of 390° C. for about 40 minutes to produce a glass substrate having a first compressive stress layer and a second compressive stress layer each having a thickness of about 17.5 μm extending inwardly from both side surfaces of the glass substrate.

[0117] [Applicable products] Information on the products mainly used in the following Production Examples, Comparative Examples and Examples is as follows. -Aluminosilicate glass: AS-87, Schott -Polyacrylate binder resin: Sumipex, Sumitomo - First dye: IRA 1032, Exciton, a diimonium compound - Second dye: IRA 705, Exciton, squarylium compound -Third dye: ADA3232, HW.SANDS, a compound having an absorption maximum in the wavelength range of 300 nm to 400 nm -Fourth dye: S0094, Few Chemicals, a cyanine compound having an absorption maximum in the range of 800 nm to 850 nm - Dispersant: Disperbyk110, BYK

[0118] Manufacturing Example 1: Laminate The laminate was prepared according to the following sequence:

[0119] i) A composition is prepared by mixing a polyacrylic binder resin with 3 parts by weight of a first dye and 500 parts by weight of methyl isobutyl ketone per 100 parts by weight of the binder resin.

[0120] ii) The composition was spin-coated onto one surface of the tempered glass substrate, and then thermally cured at 140° C. for about 2 hours to form a light absorbing layer having a thickness of about 3 μm, thereby obtaining a laminate.

[0121] Manufacturing Example 2: Laminate A laminate was obtained in the same manner as in Preparation Example 1, except that in step i), 5 parts by weight of the second dye was used instead of the first dye to prepare a composition.

[0122] Manufacturing Example 3: Laminate A laminate was obtained in the same manner as in Preparation Example 1, except that in step i), 5 parts by weight of the second dye (Exciton, product name IRA 705), 3 parts by weight of the third dye, and 0.1 parts by weight of the fourth dye were mixed instead of the first dye.

[0123] The transmittance spectrum measured for the test pieces of the light absorbing layer manufactured in the manufacturing examples 1 to 3 is shown in FIG. 5. According to FIG. 5, it can be confirmed that the first dye, specifically the maximum absorption wavelength of the light absorbing layer to which the dye is applied, is in the wavelength range of 850 nm to 1,200 nm (manufacturing example 1). Also, according to FIG. 5, it can be confirmed that the second dye, specifically the maximum absorption wavelength of the light absorbing layer to which the dye is applied, is in the range of 650 nm to 750 nm (manufacturing example 2). In this case, when the second dye and the specific dye are further blended, the light absorbing layer can have an absorption maximum due to the blended dye, without a decrease in visible light transmittance and near infrared absorptance even at wavelengths in the ranges of 300 nm to 400 nm and / or 800 nm to 850 nm (manufacturing example 3).

[0124] Manufacturing Example 4: Laminate In step i), 5 parts by weight of the first dye and 500 parts by weight of methyl isobutyl ketone were mixed with 100 parts by weight of polyacrylic binder resin, 0.2 parts by weight of a dispersant was added, and the mixture was dispersed for about 6 hours using 0.5 mm zirconia beads in a dispersing device to prepare a composition. A laminate was obtained in the same manner as in Preparation Example 1. In the light absorbing layer of Preparation Example 4, the first dye, which is a diimonium dye, was present in a dispersed state in the binder resin.

[0125] Manufacturing Example 5: Laminate In step i), 5 parts by weight of the first dye and 500 parts by weight of cyclohexanone were mixed with 100 parts by weight of the polyacrylic binder resin, so that the first dye was present in a dissolved state in the composition and was present in a form coloring the binder resin in the light absorbing layer formed therewith, and a laminate was obtained in the same manner as in Preparation Example 4.

[0126] The transmittance spectra measured for the laminates of Production Examples 4 and 5 are shown in Fig. 6, and the transmittance in the main wavelength range is shown in Table 1 below. It can be confirmed that the transmittance in the visible light range (450 nm or more and 700 nm or less) and the absorbance in the near-infrared range (approximately 1,050 nm) are higher in the light absorbing layer of Production Example 4 than in the light absorbing layer of Production Example 5. It can be confirmed that this is due to the dissolution of the first dye, causing deterioration in the layer containing it (the light absorbing layer of Production Example 2).

[0127] Through this, it can be seen that when the specific first dye applied in the present application is not dissolved in the light absorbing layer but is dispersed (in particle form) in the binder resin, a light absorbing layer having high visible light transmittance and infrared absorbance at the same time can be formed.

[0128] [Table 1]

[0129] Manufacturing Example 6: Laminate A laminate was obtained in the same manner as in Preparation Example 1, except that in step i), diethylene glycol monoethyl ether, which has a room temperature solubility of about 0 g / L for the first dye, was used instead of methyl isobutyl ketone.

[0130] Manufacturing Example 7: Laminate A laminate was obtained in the same manner as in Preparation Example 1, except that in step i), 4-hydroxy-4-methyl-2-pentanone, which has a room temperature solubility of about 5 g / L for the first dye, was used instead of methyl isobutyl ketone.

[0131] Manufacturing Example 8: Laminate A laminate was obtained in the same manner as in Preparation Example 1, except that in step i), propylene glycol methyl ether acetate, which has a room temperature solubility of about 10 g / L for the first dye, was used instead of methyl isobutyl ketone.

[0132] Manufacturing Example 9: Laminate A laminate was obtained in the same manner as in Preparation Example 1, except that in step i), chlorobenzene, which has a room temperature solubility of about 15 g / L for the first dye, was used instead of methyl isobutyl ketone.

[0133] Manufacturing Example 10: Laminate A laminate was obtained in the same manner as in Preparation Example 1, except that in step i), isophorone, which has a room temperature solubility of about 20 g / L in the first dye, was used instead of methyl isobutyl ketone.

[0134] Manufacturing Example 11. Laminate A laminate was obtained in the same manner as in Preparation Example 1, except that in step i), γ-butyrolactone, which has a room temperature solubility of about 30 g / L for the first dye, was used instead of methyl isobutyl ketone.

[0135] The transmittance spectra measured for the laminates of Preparation Examples 6 to 11 are shown in Fig. 7. It can be seen from Fig. 7 that the transmittance in the visible light region improves as the solvent having a lower solubility for the first dye is used. This shows that in order to obtain the appropriate visible light transmittance targeted in the present application (for example, an average transmittance of 85% or more for light having a wavelength in the range of 465 nm to 570 nm), it is advantageous to use a solvent having as low a solubility as possible for the first dye when producing the light absorbing layer.

[0136] Manufacturing Example 12. Near-infrared absorbing plate The near infrared absorbing plate was manufactured in the following order.

[0137] i) Composition for forming first light absorbing layer A composition for forming a first light absorbing layer in which the first dye is dispersed in the form of particles is prepared by mixing 1 part by weight of a first dye and 500 parts by weight of methyl isobutyl ketone with 100 parts by weight of a polyacrylic binder resin, adding 0.2 parts by weight of a dispersant, and dispersing the mixture at an appropriate rotation speed (rpm) using a dispersing device for approximately 6 hours.

[0138] ii) Composition for forming second light absorbing layer A composition for forming a second light absorbing layer is prepared by mixing 5 parts by weight of a second dye and 500 parts by weight of methyl isobutyl ketone with 100 parts by weight of a polyacrylic binder resin, in which the second dye dissolves and colors the binder resin.

[0139] iii) Adhesive Composition A commercially available polyacrylate resin and a polyisocyanate resin are mixed in a weight ratio of 99:1 (polyacrylate resin:polyisocyanate resin) to produce an adhesive composition.

[0140] iv) Near infrared absorbing plate A first light absorbing layer forming composition is spin-coated onto one surface of a strengthened glass substrate, and heat-treated at a temperature of about 140° C. for about 2 hours to form a first light absorbing layer having a thickness of about 3 μm.

[0141] Next, the adhesive composition is spin-coated onto the first light absorbing layer at a rotation speed of 1,000 rpm for approximately 15 seconds, and heat-treated at a temperature of approximately 130° C. for approximately 15 minutes to form an adhesive layer with a thickness of approximately 0.4 μm.

[0142] Next, the composition for forming the second light absorbing layer is spin-coated onto the adhesive layer and heat-treated at a temperature of 140°C for about 3 hours to form a second light absorbing layer with a thickness of about 3 µm, thereby producing a near-infrared absorbing plate.

[0143] Manufacturing Example 13. Near-infrared absorbing plate A near infrared absorbing plate was obtained in the same manner as in Preparation Example 12, except that in step ii), 5 parts by weight of the second dye, 3 parts by weight of the third dye, and 0.1 parts by weight of the fourth dye were mixed to prepare a composition for forming a second light absorbing layer, instead of mixing the second dye alone.

[0144] Manufacturing Example 14. Near-infrared absorbing plate i) Light-absorbing layer-forming composition A light absorbing layer-forming composition is produced by mixing 1 part by weight of a first dye, 5 parts by weight of a second dye, and 500 parts by weight of methyl isobutyl ketone with 100 parts by weight of a polyacrylic binder resin, adding 0.2 parts by weight of a dispersant, and dispersing the mixture using zirconia beads in a dispersing device, in which the first dye is present in a dispersed state and the second dye is present in a dissolved state.

[0145] ii) Near infrared absorbing plate The composition for forming a light absorbing layer was spin-coated on one surface of a tempered glass substrate and heat-treated at a temperature of about 140° C. for about 2 hours to form a light absorbing layer with a thickness of about 3 μm, thereby obtaining a near infrared absorbing plate.

[0146] According to FIG. 8, it can be seen that the near-infrared absorbing plates of Manufacturing Examples 12 and 13 have improved visible light transmittance and near-infrared absorptance compared to the near-infrared absorbing plate of Manufacturing Example 14. From this, it can be seen that the near-infrared absorbing plate has improved optical properties when the light absorbing layer of the near-infrared absorbing plate is composed of a single layer (Manufacturing Example 14) but composed of multiple layers that are distinct from each other (Manufacturing Examples 12 and 13). It can also be seen that the near-infrared absorbing plate composed of light absorbing layers containing dyes having different optical properties present separately has improved heat resistance. This is expected to be due to the fact that no interaction occurs between organic substances such as dyes having different optical properties applied to the light absorbing layer.

[0147] Manufacturing Example 15. Near-infrared absorbing plate i) Composition for forming first light absorbing layer A composition for forming a first light absorbing layer in which the first dye is dispersed in the form of particles is prepared by mixing 1 part by weight of a first dye and 500 parts by weight of diethylene glycol monoethyl ether (a solvent in which the solubility of the first dye at room temperature is approximately 0 g / L) with 100 parts by weight of a polyacrylate binder resin, adding 0.2 parts by weight of a dispersant, and dispersing appropriately using zirconia beads in a dispersing device.

[0148] ii) Composition for forming second light absorbing layer A composition for forming a second light absorbing layer is prepared by mixing 100 parts by weight of a polyacrylic binder resin with 5 parts by weight of a second dye, 3 parts by weight of a third dye, 0.1 parts by weight of a fourth dye, and 500 parts by weight of methyl isobutyl ketone.

[0149] iii) Adhesive Composition A commercially available polyacrylate resin and a polyisocyanate resin are mixed in a weight ratio of 99:1 (polyacrylate resin:polyisocyanate resin) to produce an adhesive composition.

[0150] iv) Near infrared absorbing plate A first light absorbing layer forming composition is spin-coated onto one surface of a strengthened glass substrate, and heat-treated at a temperature of about 140° C. for about 2 hours to form a first light absorbing layer having a thickness of about 3 μm.

[0151] Next, the adhesive composition is spin-coated onto the first light absorbing layer at a rotation speed of 1,000 rpm for about 15 seconds, and heat-treated at a temperature of about 130° C. for about 15 minutes to form an adhesive layer with a thickness of about 0.4 μm.

[0152] Next, the composition for forming the second light absorbing layer is spin-coated onto the adhesive layer and heat-treated at a temperature of 140°C for about 3 hours to form a second light absorbing layer with a thickness of about 3 µm, thereby producing a near-infrared absorbing plate.

[0153] Manufacturing Example 16. Near-infrared absorbing plate A near infrared absorbing plate was obtained in the same manner as in Preparation Example 15, except that in step i), 4-hydroxy-4-methyl-2-pentanone (a solvent in which the solubility of the first dye at room temperature is about 5 g / L) was mixed instead of diethylene glycol monoethyl ether.

[0154] Manufacturing Example 17. Near-infrared absorbing plate A near infrared absorbing plate was obtained in the same manner as in Preparation Example 15, except that propylene glycol methyl ether acetate (a solvent in which the solubility of the first dye at room temperature is about 10 g / L) was used instead of 4-hydroxy-4-methyl-2-pentanone in step i).

[0155] Manufacturing Example 18. Near-infrared absorbing plate A near infrared absorbing plate was obtained in the same manner as in Preparation Example 15, except that in step i), chlorobenzene (a solvent in which the solubility of the first dye at room temperature is about 15 g / L) was used instead of 4-hydroxy-4-methyl-2-pentanone.

[0156] Manufacturing Example 19. Near-infrared absorbing plate A near infrared absorbing plate was obtained in the same manner as in Preparation Example 15, except that isophorone (a solvent in which the room temperature solubility of the first dye is about 20 g / L) was used instead of 4-hydroxy-4-methyl-2-pentanone in step i).

[0157] Manufacturing Example 20. Near-infrared absorbing plate A near infrared ray absorbing plate was obtained in the same manner as in Preparation Example 15, except that in step i), γ-butyrolactone (a solvent in which the solubility of the first dye at room temperature is about 30 g / L) was used instead of 4-hydroxy-4-methyl-2-pentanone.

[0158] The transmittance spectra of the near infrared absorbing plates of Preparation Examples 15 to 20 are shown in Fig. 9. From Fig. 9, it can be seen that the near infrared absorbing plates of Preparation Examples 15 to 18 have improved visible light transmittance compared to the near infrared absorbing plates of Preparation Examples 19 and 20. From this, it can be seen that when a layer in which a first dye is present in a dispersed state in a solvent having a specific solubility is applied as the first light absorbing layer as specified in the present application, the desired properties of the present application, for example, excellent visible light transmittance, can be obtained.

[0159] Comparative Example 1: Near-infrared absorbing plate i) Composition for forming first light absorbing layer A composition for forming a first light absorbing layer in which the first dye is dispersed in the form of particles is prepared by mixing 1 part by weight of a first dye and 500 parts by weight of diethylene glycol monoethyl ether (a solvent in which the solubility of the first dye at room temperature is approximately 0 g / L) with 100 parts by weight of a polyacrylic binder resin, adding 0.2 parts by weight of a dispersant, and dispersing the mixture using zirconia beads in a dispersing device for approximately 6 hours.

[0160] ii) Composition for forming second light absorbing layer 5 parts by weight of the second dye and 500 parts by weight of methyl isobutyl ketone are mixed with 100 parts by weight of a polyacrylic binder resin to produce a composition for forming a second light absorbing layer in which the second dye is dissolved.

[0161] iii) Near infrared absorbing plate A first light absorbing layer forming composition is spin-coated onto one surface of a strengthened glass substrate, and heat-treated at a temperature of about 140° C. for about 2 hours to form a first light absorbing layer having a thickness of about 3 μm.

[0162] Next, the composition for forming the second light absorbing layer is spin-coated onto the first light absorbing layer, and heat-treated at a temperature of 140°C for about 3 hours to form a second light absorbing layer having a thickness of about 3 µm, thereby producing a near-infrared absorbing plate.

[0163] Comparative Example 2: Near-infrared absorbing plate In step iv), the near infrared ray absorbing plate was obtained in the same manner as in Preparation Example 15, except that the adhesive composition was spin-coated at a rotation speed of 3,000 rpm for about 15 seconds. At this time, the thickness of the adhesive layer was about 0.05 μm.

[0164] Comparative Example 3: Near-infrared absorbing plate In step iv), the adhesive composition was spin-coated at a rotation speed of 2,000 rpm for about 15 seconds, and the same method as in Preparation Example 15 was used to obtain a near infrared ray absorbing plate. In this case, the thickness of the adhesive layer was about 0.1 μm.

[0165] Example 1. Near-infrared absorbing plate In step iv), the adhesive composition was spin-coated at a rotation speed of 1,500 rpm for about 15 seconds, and the same method as in Preparation Example 15 was used to obtain a near infrared ray absorbing plate. In this case, the thickness of the adhesive layer was about 0.2 μm.

[0166] Example 2. Near-infrared absorbing plate A near infrared absorbing plate was obtained in the same manner as in Production Example 15.

[0167] FIG. 10 shows the transmittance spectrum of the near-infrared absorbing plates of Comparative Examples 1-3 and Examples 1-2. Table 2 shows the haze measurement results of the near-infrared absorbing plates of the Examples and Comparative Examples. From FIG. 10, it can be seen that the near-infrared absorbing plates of the Examples have improved visible light transmittance and near-infrared absorptance (or blocking rate) compared to the absorbing plates of the Comparative Examples. From Table 2, it can be seen that the near-infrared absorbing plates of the Examples have a particularly low haze, for example 0.3% or less, compared to the absorbing plates of the Comparative Examples. This can be achieved even when the first and second light absorbing layers having the above-mentioned optical properties are separated from each other. In particular, in an imaging device to which a near-infrared absorbing plate is applied, the near-infrared absorbing plate must have high transmittance in the visible light region and high absorptance in the near-infrared region, and at the same time, must have optical properties of less than 0.3% haze in the normal visible light region (for example, light with a wavelength of about 550 nm) in order to ensure image quality, and the near-infrared absorbing plate of the Examples can satisfy such a condition.

[0168] Through this, it can be seen that, in particular, when there is no adhesive layer as a separation layer between the first and second light absorbing layers as in the comparative example, or even if there is an adhesive layer, the thickness is so thin that the first and second light absorbing layers are not separated, the optical properties, for example low haze, targeted in the present application are not obtained. In other words, it can be seen that only when a plurality of light absorbing layers having specific optical properties and different from each other are arranged separately from each other as in the present application, interaction between the components constituting each light absorbing layer does not occur, and therefore a near infrared absorbing plate particularly suitable for an imaging device can be obtained.

[0169] [Table 2]

[0170] [Cross-reference to related applications] This application claims the benefit of the filing date of Patent Application No. 10-2020-0068228, filed with the Korean Intellectual Property Office on June 5, 2020, the entire contents of which are incorporated herein by reference. [Explanation of symbols]

[0171] 100 Glass substrate 200 First light absorbing layer 300 Second light absorbing layer 400 separation layer

Claims

1. A glass substrate; A first light absorbing layer having a maximum absorption wavelength in the range of 850 nm to 1,200 nm; a second light absorbing layer that is separated from the first light absorbing layer and has a maximum absorption wavelength in the range of 650 nm to 750 nm, the first light absorbing layer is a cured product of a composition including a first binder resin, a first dye dispersed in the first binder resin, and a first solvent; the second light absorbing layer includes a second binder resin, a second dye that colors the second binder resin, and a second solvent; the solubility of the first dye in the first solvent is 15 g / L or less; the solubility of the second dye in the second solvent is 15 g / L or more; A near-infrared absorbing plate having a haze of 0.3% or less.

2. The near infrared absorbing plate according to claim 1 , wherein the first light absorbing layer has a transmittance of 20% or less for light having any one wavelength within a wavelength range of 950 nm to 1,200 nm.

3. The near-infrared absorbing plate according to claim 1 or 2, wherein the second light absorbing layer has a transmittance of 5% or less for light having any one wavelength in the range of 670 nm to 730 nm.

4. The transmittance for light having a wavelength of 450 nm is 60% or more, The transmittance for light having a wavelength of 550 nm is 70% or more, The near-infrared absorbing plate according to claim 1 , which has a transmittance of 40% or less for light having a wavelength of 1,050 nm.

5. The near-infrared absorbing plate according to claim 1 , wherein the glass substrate has a three-point bending strength of 360 MPa or more as measured based on ASTM D790 standard.

6. The near-infrared absorbing plate according to claim 1 , wherein the glass substrate has a thickness in the range of 0.07 mm or more and 0.3 mm or less.

7. The near-infrared absorbing plate according to claim 1 , wherein the first light absorbing layer is present on an opposite side of the second light absorbing layer with respect to the glass substrate.

8. 7. The near-infrared absorbing plate according to claim 1, comprising the glass substrate, the first light absorbing layer, and the second light absorbing layer, in that order; or comprising the glass substrate, the second light absorbing layer, and the first light absorbing layer, in that order.

9. The near infrared absorbing plate according to claim 8 , further comprising a separation layer present between the first light absorbing layer and the second light absorbing layer.

10. The near infrared absorbing plate according to claim 9 , wherein the separation layer is an adhesive layer.

11. The near-infrared absorbing plate according to claim 9 or 10, wherein the separation layer has a thickness of 0.2 μm or more.

12. 12. The near-infrared absorbing plate according to claim 1, wherein the glass substrate includes a first compressive stress layer present on a first main surface of the glass substrate, and a second compressive stress layer present on a second main surface that is a main surface opposite to the first main surface.

13. A near-infrared absorbing plate as described in claim 1, wherein the solubility of the first binder resin in the first solvent is 100 g / L or more.

14. The near infrared absorbing plate according to claim 1 , wherein the first dye comprises a compound represented by the following Chemical Formula 1: 【Chemistry 1】 In Formula 1, R1 to R8 are each independently a hydrogen atom, an alkyl group, an aryl group, an aralkyl group, an alkenyl group, or an alkynyl group; R9 to R11 are each independently a hydrogen atom, a halogen group, an amino group, a cyano group, a nitro group, a carboxy group, an alkyl group, or an alkoxy group; and X- is an anion.

15. The near infrared absorbing plate according to claim 1 , wherein the second dye comprises a compound represented by the following Chemical Formula 2: 【Chemistry 2】

16. 16. The near infrared absorbing plate according to claim 15, wherein, in Chemical Formula 2, at least one of hydrogen atoms present in the aminophenyl group, the indolylmethylene group, the indolinyl group, or the pyrimidine group is independently substituted with an aryl group having 6 to 20 carbon atoms, and at least one hydrogen atom in the aryl group is further substituted with an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms.

17. 17. An optical filter comprising: the near-infrared absorbing plate according to claim 1; and a selective wavelength reflecting layer present on one or both sides of the near-infrared absorbing plate.

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