JP7232918B2 - Light-shielding film and method for producing light-shielding film - Google Patents

Description

The present invention relates to a light-shielding film and a method for producing a light-shielding film. Specifically, the present invention relates to a light-shielding film used for optical applications, opto-device applications, display device applications, mechanical parts, electric/electronic parts, and the like, and a method for producing the light-shielding film.

A light-shielding film is used for the purpose of suppressing the generation and expansion of optical noise in a lens unit in a camera module, which is an optical component provided in electronic devices such as digital cameras and mobile phones, for example. A light-shielding film is also used as a gap adjusting member arranged between optical elements such as a shutter, a diaphragm member, or a lens in a camera module.

As the light-shielding film, for example, a black film is used in which polyethylene terephthalate (PET) is colored black by adding carbon black and light-shielding properties are imparted by forming unevenness on the surface. Further, for example, Patent Document 1 discloses light-shielding films 20 and 21 having a structure in which a light-shielding layer 202 is superimposed on at least one surface of a film substrate 201, as shown in FIGS. there is The light shielding layer 202 is composed of a resin, which is a curable resin or a thermosetting resin, and black fine particles.

Such light-shielding films 20 and 21 are used as light-shielding films F7 and F8 in a conventional lens unit 30 shown in FIG. A lens unit 30 shown in this figure includes a sensor lens 33 housed in a barrel 32, an infrared cut filter 31, and a plurality of lenses L7 and L8. The light-shielding films 20 and 21 in FIGS. 5 and 6 are provided as light-shielding films F7 and F8 individually corresponding to the lenses L7 and L8 in FIG. In the lens unit 30, light-shielding films F7 and F8, one or more lenses L7 and L8, and a CMOS sensor are arranged in this order along the traveling direction of incident light. By separately providing the light shielding films F7 and F8 corresponding to the lenses L7 and L8, unnecessary light can be sufficiently blocked.

Japanese Patent Publication No. 2010-534342

In recent years, there has been a growing demand for camera modules to be smaller, thinner, and lighter in accordance with the devices in which they are mounted. In addition, camera modules are required to have advanced functions such as a wider-range zoom function and a high-definition imaging function using fine pixels. Such high functionality is difficult with digital processing, and for example, it is necessary to improve the optical zoom function of the lens unit provided in the camera module.

However, in order to improve the functionality of the lens unit, it is necessary to increase the number of lenses, for example. When arranging a light-shielding film corresponding to each lens, the total thickness of the light-shielding film increases as the number of lenses increases. As a result, the optical axis direction of the lens unit increases, making it difficult to reduce the size of the lens unit. If the device on which the camera module is mounted is a smartphone or the like, this may cause the lens unit to protrude from the housing, resulting in design problems for the device. This problem becomes conspicuous according to the number of sheets of the light-shielding film.

As a countermeasure for this problem, for example, it is conceivable to reduce the thickness of the light-shielding film. However, if the thickness of the light-shielding film is simply reduced, the light-shielding properties of the light-shielding film will deteriorate. In this way, in order to achieve both miniaturization and high functionality of the camera module, it is necessary to adjust the thickness while maintaining the performance of the light-shielding film.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to reduce the thickness of a light-shielding film while maintaining good light-shielding properties.

In order to solve the above problems, a light-shielding film according to an aspect of the present invention has a glossiness of at least one surface at an incident angle of 60 degrees set to a value in the range of 0 or more and 10 or less, and has a wavelength of 380 nm or more and 780 nm or less. The optical density is set to a value in the range of 4 or more, and the total thickness is set to a value in the range of 6 μm or more and 26 μm or less.

According to the above configuration, the glossiness of at least one surface of the light-shielding film is set to a value in the range of 0 or more and 10 or less, so that the surface has high light scattering properties (reflection preventive properties). In addition, since the optical density of the light-shielding film is set to a value in the range of 4 or more and the total thickness is set to a value in the range of 6 μm or more and 26 μm or less, good light-shielding can be achieved even if the thickness of the light-shielding film is reduced. can retain their sexuality.

A light-shielding film substrate and a scattering layer disposed over the film substrate to scatter incident light, wherein the one surface of the scattering layer is the opposite side of the film substrate. It may be the surface.

As a result, for example, even if the thickness of the scattering layer is reduced, the light-shielding effect of the light-shielding film can be favorably maintained by the light-shielding film substrate. Therefore, the total thickness of the light-shielding film can be easily reduced. Moreover, good light-scattering properties can be obtained on the surface of the scattering layer opposite to the light-shielding film substrate. In addition, by using a scattering layer separate from the light-shielding film substrate, the degree of freedom in designing the scattering layer can be improved.

The content of the black component in the scattering layer may be set to a value in the range of more than 0% by weight and 4% by weight or less. In the light-shielding film, since the film substrate has light-shielding properties, the content of the black component in the scattering layer may be very small. Even with such a configuration, the light-shielding property of the light-shielding film can be ensured.

Further, in the above configuration, the amount of black component in the scattering layer is suppressed. Therefore, even when the scattering layer is formed using, for example, an ultraviolet-curing resin material, the scattering layer can be satisfactorily formed by irradiating ultraviolet rays to cure the resin material. According to this method, heat is less likely to reach the light-shielding film substrate than in the method of forming the scattering layer using a thermosetting resin material. Therefore, the light-shielding film substrate is less likely to thermally shrink, so that the thickness of the light-shielding film substrate can be reduced. As a result, the total thickness of the light-shielding film can be reduced.

The scattering layer may further include a resin member arranged along the surface of the film substrate and particles dispersed inside the resin member. According to this configuration, the particles can impart an uneven shape to the surface of the scattering layer. Moreover, the light scattering property inside the scattering layer can be improved. Thereby, the light scattering property can be favorably imparted to the scattering layer.

The thickness of the film substrate may be set to a value in the range of 2 μm or more and 12 μm or less. According to such a configuration, by using the light-shielding film base, the thickness of the light-shielding film base can be favorably reduced while maintaining the light-shielding properties of the light-shielding film.

The thickness of the scattering layer may be set to a value in the range of 3 μm or more and 7 μm or less. In the light-shielding film, the film substrate has a light-shielding property, and the scattering layer does not have to have a light-shielding property, so that the thickness of the scattering layer can be reduced. Therefore, the total thickness of the light-shielding film can be reduced.

The total light transmittance of the scattering layer may be set to a value in the range of 70% or more and 100% or less. By configuring the scattering layer in this way, the blackness of the light-shielding film can be favorably obtained by the film substrate having the light-shielding property.

A refractive index of the resin member may be set to a value in the range of 1.3 or more and 1.9 or less. By configuring the scattering layer in this manner, the incident light entering the scattering layer can be easily scattered.

A method for producing a light-shielding film according to an aspect of the present invention comprises a preparation step of preparing a coating liquid containing a resin material having UV-curing and electron beam-curing properties, and a film substrate having light-shielding properties; A first step of applying the coating liquid to the surface of a film substrate and drying it to form a coating film on the surface and irradiating the coating film with ultraviolet rays; and a second step of irradiating an electron beam, and through the first step and the second step, from the coating film to the surface opposite to the film substrate at an incident angle of 60 degrees A scattering layer having a glossiness set to a value in the range of 0 to 10 is provided, the film substrate and the scattering layer are provided, and the optical density is 4 or more in the wavelength range of 380 nm to 780 nm. A light-shielding film having a total thickness set to a value within a range of 6 μm or more and 26 μm or less is formed.

According to the above manufacturing method, since the glossiness is set to a value in the range of 0 to 10, high light scattering properties can be exhibited, and the optical density is set to a value in the range of 4 or more, and the total thickness is reduced. A light-shielding film having a thickness in the range of 6 μm or more and 26 μm or less can be produced. Therefore, it is possible to obtain a light-shielding film capable of maintaining good light-shielding properties in spite of its relatively small total thickness.

Further, by performing the second step in addition to the first step, the coating film can be cured satisfactorily even when the coating film contains a black component to some extent. Moreover, heat treatment for curing the scattering layer is not required. Therefore, there is no thermal shrinkage of the light-shielding film substrate during production of the light-shielding film. Therefore, shrinkage of the film substrate can be prevented even if the thickness of the film substrate having a light-shielding property is reduced to some extent. Thereby, the total thickness of the light-shielding film can be reduced.

In the second step, a transfer member having a transfer surface on which unevenness is formed is arranged such that the transfer surface adheres to the surface of the coating film opposite to the film substrate, and the coating is performed. The scattering layer may be formed by irradiating the film with electron beams to which the uneven shape is transferred. Thereby, the uneven shape formed on the transfer surface of the transfer member can be efficiently transferred to the surface of the scattering layer.

In the first step, the coating film is formed on both sides of the film substrate, and in the second step, from one side of the film substrate, the coating film is applied to the film substrate so as to pass through the film substrate. You may irradiate an electron beam to each said coating film by irradiating an electron beam. As a result, the scattering layers can be efficiently arranged on both sides of the light-shielding film substrate at the same time.

In the preparation step, the coating liquid may be prepared so that the content of the black component in the scattering layer is in the range of more than 0% by weight and 4% by weight or less. Thereby, the transmittance of the coating film to ultraviolet rays and electron beams can be maintained. Therefore, the scattering layer can be satisfactorily formed using the resin material.

In the preparing step, the coating liquid further containing particles may be prepared. According to this method, the surface of the scattering layer can be formed into an uneven shape by the particles. Moreover, the light scattering property inside the scattering layer can be improved. Therefore, the light scattering property can be easily imparted to the scattering layer.

In the second step, the scattering layer including a resin member having a refractive index set to a value within the range of 1.3 or more and 1.9 or less may be formed. Thereby, a scattering layer that easily scatters incident light can be formed.

In the preparing step, the film substrate having a thickness set to a value in the range of 2 μm or more and 12 μm or less may be prepared. According to the above production method, the thickness of the light-shielding film substrate can be favorably reduced while maintaining the light-shielding property of the light-shielding film. In addition, since the scattering layer is formed through the first step and the second step, heat is less likely to reach the film member. Therefore, even if such a thin film substrate having a light-shielding property is used, the film member shrinks due to heating associated with the formation of the scattering layer, and wrinkles, waves, curls, etc. occur, and processing such as punching cannot be performed normally. You can prevent difficult problems from occurring.

In the second step, the scattering layer having a thickness set to a value in the range of 3 μm or more and 7 μm or less may be formed from the coating film. In the light-shielding film, the film substrate has a light-shielding property, and the scattering layer does not have to have a light-shielding property, so that the thickness of the scattering layer can be reduced. Therefore, the total thickness of the light-shielding film can be easily reduced.

In the second step, a scattering layer having a total light transmittance set to a value in the range of 70% or more and 100% or less may be formed from the coating film. By configuring the scattering layer in this way, the resin material in the coating liquid can be efficiently cured by allowing electron beams to pass through the resin material in the coating liquid from the outside.

According to each aspect of the present invention, the thickness of the light-shielding film can be reduced while maintaining good light-shielding properties.

3 is an exploded view of the optical component according to the first embodiment; FIG. 1 is a cross-sectional view of a light-shielding film according to a first embodiment; FIG. (a) is a diagram showing a coating film forming step. (b) is a diagram showing a first step. (c) is a cross-sectional view showing a second step. FIG. 8 is an enlarged cross-sectional view of a scattering layer of a light-shielding film according to a second embodiment; 1 is a cross-sectional view of a conventional light-shielding film; FIG. 1 is a cross-sectional view of a conventional light-shielding film; FIG. It is a partial cross section of a conventional lens unit.

Hereinafter, each embodiment will be described with reference to the drawings.

(First embodiment)
[Light-shielding film]
FIG. 1 is an exploded view of an optical component 10 according to the first embodiment. As shown in FIG. 1, the optical component 10 includes a plurality of light-shielding films F1 to F6, a plurality of optical members (here, lenses L1 to L6), and a housing that accommodates the light-shielding films F1 to F6 and the optical members. (Lens barrel) 11 is provided. As an example, the light-shielding film 1 is arranged so as to surround the optical axis R between adjacent optical members. The number of light-shielding films included in the optical component 10 and the number of optical members are not limited.

Next, a specific configuration example of the light-shielding film 1 will be described. FIG. 2 is a cross-sectional view of the light-shielding film 1 according to the first embodiment. The light-shielding film 1 is similar to the light-shielding films F1 to F6 in FIG. As shown in FIG. 2 , the light-shielding film 1 of this embodiment includes a light-shielding film substrate 2 and at least one scattering layer 3 .

The film substrate 2 shields incident light that has entered the light-shielding film 1 . The optical density (OD value) of the film substrate 2 is set to a value in the range of 4 or more. Here, the film substrate 2 has a total light transmittance set to a value in the range of 1% or less. The film substrate 2 is opaque as an example because it has a light-shielding property, and is black here. The film base material 2 contains a black component and resin as an example. In this embodiment, the black component is a black pigment and the resin is PET. The film substrate 2 is formed by extruding and biaxially stretching a PET resin containing a black pigment. The black component may be other than pigment (for example, dye or colorant). The film substrate 2 may be colored in a color other than black.

Examples of materials for the film substrate 2 include various polymer materials. Examples of such materials include thermosetting resins, thermoplastic resins, and photocurable resins. Examples of thermoplastic resins include polyolefins, acrylic resins, polyesters, polycarbonates, and polyamides. These materials can be used singly or in combination of two or more. Among these, cyclic polyolefins, polyalkylene arylates (polyethylene terephthalate (PET), polyethylene naphthalate (PEN), etc.), polymethyl methacrylate resins, bisphenol A polycarbonate, cellulose esters, and the like are preferable from the viewpoint of ensuring strength. From the viewpoint of dimensional stability and rigidity, a biaxially stretched film material is preferred. As such a film material, a film made of biaxially stretched polyalkylene arylate (for example, PET film, PEN film) is more preferable. Among these, the PET film is preferable because it can be made thin and is easily available.

A method for manufacturing the film substrate 2 is not particularly limited. For example, there is a production method in which a material obtained by melt-kneading a black component (eg, a pigment, a dye, or a coloring agent) and a resin component is formed into a film and stretched. According to the manufacturing method of this aspect, the film substrate 2 having a light-shielding property can be constructed in a single structure without stacking a plurality of materials, which is preferable.

Moreover, as a manufacturing method of the film substrate 2, there is a manufacturing method of forming a colored layer on one side or both sides of a resin film (for example, a biaxially stretched polyester film). In the case of the manufacturing method for forming the colored layer, the colored layer may be formed by coating, transferring, or printing the coloring agent on the resin film. In this case, the colorant can be used in a state of being mixed with, for example, a fluid resin material.

Examples of the method of applying the colorant include known methods such as gravure coater, dip coater, reverse roll coater, and extrusion coater. Further, as a method for printing the colorant, known methods such as an inkjet method and a screen method can be exemplified. As the colorant to be applied, transferred, or printed on the resin film, it is preferable to use, for example, a sublimation dye from the viewpoint of easiness of permeation into the resin film. In addition, dyes that are widely used in fiber applications, resin applications, inkjet applications, and the like can also be used.

In addition, there is a production method of dyeing the resin film by immersing the resin film in a solution containing a dye. A known method can be used as a method for dyeing the resin film. In this embodiment, the resin film dyed in this manner can also be used as the film substrate 2 . Films made of polyester, nylon, acetate, polycarbonate, acrylic, etc. can be easily dyed by immersion in water-dispersed dyes.

The thickness of the film substrate 2 can be set as appropriate, but as an example, it is set to a value in the range of 2 μm or more and 12 μm or less. The film substrate 2 has an optical density of 4 or more in the wavelength range of 380 nm or more and 780 nm or less, thereby making it difficult for incident light to pass through its side surfaces.

The scattering layer 3 is superimposed on at least one surface (here, both surfaces) of the film substrate 2 and scatters incident light. The scattering layer 3 has optical transparency. For example, when the scattering layer 3 is arranged to overlap with the optical member, the scattering layer 3 scatters the incident light incident on the optical member from the side. The scattering layer 3 of this embodiment has a resin member 4 arranged along the surface of the film substrate 2 and black fine particles 5 as a black component dispersed inside the resin member 4 .

The black component of the scattering layer 3 absorbs incident light incident on the scattering layer 3 . The content of the black component in the scattering layer 3 is set to a value in the range of more than 0% by weight and 4% by weight or less. That is, the content of the black component in the scattering layer 3 is set to be very small. Thereby, the scattering layer 3 has transparency. The scattering layer 3 of this embodiment has a total light transmittance set to a value in the range of 70% or more and 100% or less. Note that the scattering layer 3 may not contain a black component.

Here, the total light transmittance of the scattering layer 3 can be obtained from the difference between the total light transmittance of the light shielding film 1 and the total light transmittance of the film substrate 2 . When the scattering layers 3 are formed on both sides of the film substrate 2, the difference between the total light transmittance of the light-shielding film 1 and the total light transmittance of the film substrate 2 is the total light transmittance of the scattering layers 3 on both sides. It corresponds to the sum of light transmittance. The total light transmittance of the film substrate 2 is equal to or higher than the total light transmittance of the light-shielding film 1 and sufficiently smaller than the total light transmittance of the scattering layer 3 . As an example, the total light transmittance of the light-shielding film 1 is 0, and the total light transmittance of the film substrate 2 is equal to or slightly higher than the total light transmittance of the light-shielding film 1 . On the other hand, the total light transmittance of the scattering layer 3 is a value in the range of 70 or more and 100 or less.

Although the thickness of the scattering layer 3 can be set as appropriate, as an example, the thickness is set to a value in the range of 3 μm or more and 7 μm or less. The thickness of the scattering layer 3 may be smaller than the thickness of the film substrate 2 . In the light-shielding film 1, the light-shielding property is ensured by the film substrate 2, so the thickness of the scattering layer 3 can be reduced. The refractive index of the resin member 4 is set to a value within the range of 1.3 or more and 1.9 or less.

The refractive index of the resin member 4 is unique to the material of the resin member 4, and can be confirmed by analyzing the resin member 4 using an analyzer such as NMR or IR. In other words, the resin member 4 of the scattering layer 3 can be specified by measuring the scattering layer 3 with an analyzer such as NMR and IR. The value of the refractive index of the resin member 4 may be either a literature value or an actual measurement value. Further, when the total light transmittance of the scattering layer 3 is sufficiently high, an Abbe refractometer conforming to JIS K 7142:2008, or an ellipsometer (for example, "KOBRA-WPR" manufactured by Oji Scientific Instruments Co., Ltd.) ) may be used to directly measure the Abbe number of the scattering layer 3 , and the measured value may be used as the value of the refractive index of the resin member 4 .

In the light-shielding film 1, the glossiness of at least one surface (here, both surfaces) of the scattering layer 3 at an incident angle of 60 degrees is set to a value in the range of 0 or more and 10 or less, and the glossiness is set to a value in the range of 380 nm or more and 780 nm or less. The optical density in the values is set to a value in the range of 4 or more, and the total thickness is set to a value in the range of 6 μm or more and 26 μm or less.

By setting the surface 3a of the scattering layer 3 in this way, the surface 3a has a light scattering property. As will be described later, the shape of the surface 3a of the scattering layer 3 is formed by transferring the unevenness of the transfer surface 8a of the transfer member 8 during the production of the light-shielding film 1, for example. The shape of the surface 3a of the scattering layer 3 may be formed by other methods. An adhesive layer may be provided on the surface of the film substrate 2 facing the scattering layer 3 to improve the adhesiveness between the film substrate 2 and the scattering layer 3 .

The resin member 4 contains a binder resin 6 and a polymerization initiator that is a precursor of the binder resin 6 . The precursor of the binder resin 6 has ultraviolet (UV) curability and electron beam (EB) curability. Examples of the binder resin 6 include photocurable resins.

Black components contained in the film substrate 2 and the scattering layer 3 include, for example, carbon black, lamp black, vine black, peach black, bone char, carbon nanotubes, silver oxide, zinc oxide, magnetite-type triiron tetroxide, copper and chromium. complex oxides of copper, chromium and zinc, and black glass.

The black fine particles 5 of this embodiment are spherical, and the primary particle size is set to a value in the range of 10 nm or more and 500 nm or less. Further, the surface resistance value of the scattering layer 3 is set to a value of 1×10 ¹² Ω/□ or more, as an example. By performing such setting, the light-shielding film 1 can be suitably used as an insulating member.

Also, the glossiness at 60 degrees can be measured by a measuring method based on JlS Z8741. The primary particle size is determined by taking a photograph of the particle surface magnified 100,000 times with a field emission scanning electron microscope (manufactured by JEOL Ltd., "JSM-6700F"), and further enlarging the magnified photograph as necessary. For 50 or more particles, a ruler, vernier caliper, or the like can be used, and the average particle size of the number can be measured.

The optical density was measured by using an optical densitometer (manufactured by Videojet X-Rite Co., Ltd., "X-Rite 341C"), irradiating the sample with a vertical transmitted light flux, and comparing the ratio to the state without the sample by log (logarithm). can be expressed as The beam width in this case can be measured as a circle with a diameter of 2 mm.

As described above, in the present embodiment, the glossiness of at least one surface of the light-shielding film 1 is set to a value in the range of 0 or more and 10 or less. Light-scattering property (anti-reflection property) can be imparted. Further, since the optical density of the light-shielding film 1 is set to a value in the range of 4 or more and the total thickness is set to a value in the range of 6 μm or more and 26 μm or less, the thickness of the light-shielding film 1 can be reduced. light shielding property can be maintained.

Further, as a result, the total thickness of the plurality of light-shielding films 1 can be reduced. Even if there is, the dimension of the housing 11 in the direction of the optical axis R can be reduced. Thereby, the dimension of the optical component 10 including the housing 11 in the direction of the optical axis R can be reduced. Therefore, the thickness and size of the optical component 10 can be easily reduced. In addition, by reducing the size of the housing 11, the area of the surface of the optical component 10 that overlaps with the housing 11 is suppressed from protruding to the outside compared to the peripheral area of the area, and the surface of the optical component 10 can be made easier to flatten.

In addition, the light-shielding film 1 of the present embodiment includes a film substrate 2 and a scattering layer 3 placed over the film substrate 2 to scatter incident light. is the surface 3 a of the scattering layer 3 opposite to the film base 2 .

Thereby, for example, even if the thickness of the scattering layer 3 is reduced, the light shielding effect of the light shielding film 1 can be maintained by the film substrate 2 . Therefore, the total thickness of the light-shielding film 1 can be easily reduced. Also, the surface 3a of the scattering layer 3 opposite to the film substrate 2 can have good light scattering properties. In addition, by using the scattering layer 3 that is separate from the film substrate 2, the degree of freedom in designing the scattering layer 3 can be improved.

Moreover, the scattering layer 3 of the present embodiment has optical transparency. As a result, when the scattering layer 3 is made of, for example, an ultraviolet-curable or electron-beam-curable resin material, it is possible to prevent ultraviolet rays and electron beams from being shielded by components present in the resin material. Therefore, the scattering layer 3 can be formed well. Further, since it is not necessary to use a thermosetting resin material as the material of the scattering layer 3, the scattering layer 3 can be obtained by irradiating the resin material with ultraviolet rays or electron beams even on a thin film. be able to.

Further, in the scattering layer 3 of the present embodiment, the content of the black component is set to a value in the range of more than 0% by weight and 4% by weight or less. In the light-shielding film 1, since the film substrate 2 has a light-shielding property, the content of the black component in the scattering layer 3 may be very small. Even with such a configuration, the light-shielding property of the light-shielding film 1 can be ensured.

Also, the thickness of the film substrate 2 is set to a value in the range of 2 μm or more and 12 μm or less. According to such a configuration, by using the film substrate 2, the thickness of the film substrate 2 can be satisfactorily reduced while maintaining the light shielding property of the light shielding film 1. FIG. In addition, since the light-shielding film 1 does not need to form the scattering layer 3 by thermosetting, even if the thickness of the film substrate 2 is reduced in this way, the problem caused by the heat shrinkage of the film substrate 2 does not occur. You can prevent it from happening.

Moreover, the scattering layer 3 is not required to have a light shielding property. Therefore, the thickness of the scattering layer 3 of this embodiment is set to a value in the range of 3 μm or more and 7 μm or less. In the light-shielding film 1, the film substrate 2 has a light-shielding property, and the scattering layer 3 does not have to have a light-shielding property, so that the thickness of the scattering layer 3 can be reduced. Therefore, the total thickness of the light-shielding film 1 can be reduced.

The scattering layer 3 has a total light transmittance set to a value in the range of 70% or more and 100% or less. By configuring the scattering layer 3 in this way, the blackness of the light-shielding film 1 can be favorably obtained by the film substrate 2 . Such a scattering layer 3 can be configured by, for example, curing a resin material with ultraviolet rays or electron beams. The scattering layer 3 has a refractive index set to a value in the range of 1.3 to 1.9. As a result, the incident light entering the scattering layer 3 can be easily scattered.

[Method for producing light-shielding film]
Next, a method for producing the light-shielding film 1 will be illustrated. FIG. 3 is a manufacturing flow diagram of the light-shielding film 1 of FIG. FIG. 3(a) is a diagram showing the first step S2. FIG.3(b) is a figure which shows 1st step S2. FIG.3(c) is a figure which shows 2nd step S3.

The light-shielding film 1 manufacturing method of this embodiment has a preparation step S1, a first step S2, a second step S3, and a peeling step S4. The light-shielding film 1 is manufactured by sequentially performing steps S1 to S4. Steps S1 to S4 will be specifically described below.

In a preparation step S<b>1 , the operator prepares the coating liquid, which is the source of the scattering layer 3 , and the film substrate 2 . Specifically, the operator dissolves an ultraviolet curable and electron beam curable resin material in a solvent. After that, the operator adds a black component (black fine particles 5 in this embodiment) to this solvent, as an example. A coating liquid is thus obtained.

Here, the operator adjusts the coating liquid so that the solid content concentration is more than 5 wt % and 50 wt % or less (here, 30 wt % as an example). In the present embodiment, since it is necessary to cure the resin material having ultraviolet curable and electron beam curable properties, a polymerization initiator for the resin material is further added to the coating liquid. In addition, when the resin material having ultraviolet curable property is not used, the polymerization initiator is naturally unnecessary.

Also, the operator prepares the film substrate 2 having a light-shielding property manufactured by the manufacturing method described above. An operator sets the film substrate 2 on a predetermined coater. The preparation step S1 is thus completed.

Next, the operator performs the first step S2 in the following procedure. The first step S2 is a step of applying the above-prepared coating solution to the surface of the film substrate 2 and drying it to form a coating film 15 on the surface, and then irradiating the coating film 15 with ultraviolet rays. be. As an example, the first step S2 includes a coating film forming step, a transfer step, and an ultraviolet irradiation step as substeps.

Specifically, the operator applies the coating liquid to at least one surface of the film substrate 2 . In this embodiment, as an example, a coating liquid is applied to each surface of the film substrate 2 in order to form the coating films 15 on both surfaces of the film substrate 2 . The coating liquid may be applied to each surface of the film substrate 2 successively.

Thereafter, the operator dries the coating liquid applied to each surface of the film substrate 2 with wind (here, hot air) to form coating films 15 on both surfaces of the film substrate 2 (FIG. 3). (a)). This completes the coating film forming step. The coating film 15 of this embodiment has a smooth surface immediately after being formed, and is not completely cured.

Next, the operator uses a transfer member 8 having a predetermined transfer surface 8a and performs a transfer step of transferring the surface shape of the transfer surface 8a of the transfer member 8 onto the surface of the coating film 15 according to the following procedure. When the surface shape formed on the coating film 15 is positive, the transfer surface 8a of the transfer member 8 has a negative shape corresponding to this positive shape. In this embodiment, as the transfer member 8, a film member having an ultraviolet ray transmittance and an electron beam transmittance is used.

The operator adheres the transfer member 8 to the coating film 15 formed on at least one surface of the film substrate 2 . As a result, a composite (hereinafter referred to as an intermediate 16) is formed by bonding the transfer member 8 to each coating 15 of the film substrate 2. As shown in FIG. In the intermediate body 16 , the surface shape of the transfer surface 8 a of the transfer member 8 acts as a negative type, and the positive type surface shape is transferred to the coating film 15 . This completes the transfer step.

Next, the operator performs the first step S2 of irradiating the intermediate 16 with ultraviolet light according to the following procedure. (Fig. 3(b)). As a result, the surface of the coating film 15 in contact with the transfer surface 8a is cured to some extent while the transfer member 8 is attached.

A transfer surface 8a of the transfer member 8 having a negative shape is formed with fine irregularities. The scattering layer 3 is imparted with a light scattering property by transferring the fine unevenness. In this embodiment, since a film member having ultraviolet and electron beam transparency is used as the transfer member 8 , part of the resin material in the coating film 15 is cured by ultraviolet rays through the transfer member 8 . 1st step S2 is completed above. After the first step S2, the obtained intermediate 16 is wound into a roll.

Here, the transfer member 8 of this embodiment will be described. The transfer member 8 contains a plurality of resin components. The transfer surface 8a has a sea-island-like fine unevenness formed of a phase-separated structure. The surface 3 a of the scattering layer 3 has a light scattering property due to the shape of the transfer surface 8 a of the transfer member 8 . The phase-separated structure is formed by spinodal decomposition (wet spinodal decomposition) from the liquid phase of the adjustment liquid from which the transfer member 8 is made. For details of the phase separation structure, see Japanese Patent No. 6190581, for example.

In this embodiment, the coating film 15 of the intermediate 16 after the first step S2 and before the second step S3 is not completely cured. The coating film 15 has, for example, an uncured portion unevenly distributed on the film substrate 2 side. In order to obtain the light-shielding film 1, the coating film 15 must be completely cured. In yet another embodiment, the coating film 15 may be completely cured only by the ultraviolet irradiation step of the first step S2. In this case, the following second step S3 can be omitted.

Next, the operator unwinds the wound intermediate 16 again, and performs the second step S3 of irradiating the coating film 15 irradiated with the ultraviolet rays in the first step S2 with an electron beam. Thereby, the resin material in the coating film 15 is completely cured and the surface shape of the scattering layer 3 is formed.

According to the second step S3, the adhesion strength between the film substrate 2 and the scattering layer 3 can be improved. Therefore, the second step S3 is suitable when manufacturing the light-shielding film 1 including the film substrate 2 and the scattering layer 3 as in the present embodiment. In the second step S3, the intermediate 16 may be irradiated with an electron beam from only one side or from both sides.

For example, when the adhesion strength between the film substrate 2 and the scattering layer 3 is sufficient, the irradiation intensity of the electron beam may be weakened or the second step S3 may be omitted. That is, the second step S3 can be appropriately set or omitted depending on the adhesion strength between members required in the light-shielding film 1 and the like.

Also, in the second step S3, the electron beam may not be used. For example, when the second step S3 is performed while the transfer member 8 is not placed on the coating film 15, it is possible to use ultraviolet rays in the second step S3. When the transfer member 8 is placed on the coating film 15, it is desirable to use an electron beam in the second step S3.

Further, the intermediate 16 may not be wound between the first step S2 and the second step S3. For example, the first step S2 and the second step S3 may be performed continuously without winding the intermediate 16 according to the embodiment.

Next, the operator performs a peeling step S<b>4 for peeling the transfer member 8 from the intermediate body 16 . When the transfer members 8 are arranged on both surfaces of the film substrate 2 as in the present embodiment, the transfer members 8 may be peeled off simultaneously, or one of them may be peeled off in order. As described above, the light-shielding film 1 is obtained through the peeling step S4.

According to the above manufacturing method, the glossiness at an incident angle of 60 degrees on the surface is set to a value in the range of 0 or more and 10 or less, so that high light scattering properties can be exhibited and the optical density is a value in the range of 4 or more. , and the total thickness is set to a value in the range of 6 μm or more and 26 μm or less. Therefore, it is possible to obtain the light-shielding film 1 that can maintain high light-shielding properties even if the total thickness is small.

Further, by performing the second step S3 in addition to the first step S2, the coating film 15 can be cured satisfactorily even when the coating film 15 contains a black component to some extent. Further, heat treatment for curing the scattering layer 3 is not required. Therefore, there is no heat shrinkage of the film substrate 2 during the production of the light-shielding film 1 . Therefore, even if the thickness of the film substrate 2 is reduced to some extent, the shrinkage of the film substrate 2 can be prevented. Thereby, the total thickness of the light-shielding film 1 can be reduced.

Further, in the second step S3 of the present embodiment, the transfer member 8 having the transfer surface 8a on which the unevenness is formed is applied so that the transfer surface 8a adheres to the surface of the coating film 15 opposite to the film substrate 2. By irradiating the coating film 15 with an electron beam in the state of being placed in the above state, the scattering layer 3 having the concavo-convex shape transferred thereto is formed. Thereby, the uneven shape formed on the transfer surface 8 a of the transfer member 8 can be efficiently transferred to the surface 3 a of the scattering layer 3 . Moreover, even if the coating film 15 does not contain particles such as silica fine particles, the scattering layer 3 can be provided with light scattering properties.

Further, in the first step S2 of the present embodiment, the coating film 15 is formed on both surfaces of the film substrate 2, and in the second step S3, the film substrate 2 is coated from one side so as to pass through the film substrate 2. Each coating film 15 is irradiated with an electron beam by irradiating the electron beam onto the coating film 15 . Thereby, the scattering layers 3 can be efficiently arranged on both surfaces of the film substrate 2 at the same time.

In addition, in the preparation step S1 of the present embodiment, a coating liquid is prepared in which the content of the black component in the scattering layer 3 is set to be in the range of more than 0% by weight and 4% by weight or less. As a result, it is possible to satisfactorily prevent the black component from lowering the transmittance of the coating liquid to ultraviolet rays and electron beams, and to efficiently form the scattering layer 3 from the coating liquid.

Further, in the preparation step S1, as an example, the film substrate 2 having a thickness set to a value in the range of 2 μm or more and 12 μm or less is prepared. As a result, the thickness of the film substrate 2 can be favorably reduced while maintaining the light shielding properties of the light shielding film 1 . Further, since the scattering layer 3 is formed through the first step S2 and the second step S3, the film substrate 2 is less likely to be heated. Therefore, even if such a thin film base material 2 is used, the film base material 2 shrinks due to the heat associated with the formation of the scattering layer 3, and wrinkles, waves, curls, etc. occur, and processing such as punching cannot be performed normally. You can prevent difficult problems from occurring.

Further, in the second step S3, as an example, the scattering layer 3 is formed from the coating film 15 so that the thickness is set to a value in the range of 3 μm or more and 7 μm or less. In the light-shielding film 1, the film substrate 2 has a light-shielding property, and the scattering layer 3 does not have to have a light-shielding property, so that the thickness of the scattering layer 3 can be reduced. Therefore, the total thickness of the light-shielding film 1 can be easily reduced.

Further, in the second step S3, as an example, the scattering layer 3 is formed from the coating film 15 so that the total light transmittance is set to a value in the range of 70% or more and 100% or less. By configuring the scattering layer 3 in this manner, the resin material in the coating liquid can be efficiently cured by allowing electron beams to pass through the resin material in the coating liquid from the outside.

Further, in the second step S3, as an example, the scattering layer 3 having a refractive index set to a value within the range of 1.3 or more and 1.9 or less is formed. Thereby, the scattering layer 3 that easily scatters incident light can be formed. Other embodiments will be described below, focusing on differences from the first embodiment.

(Second embodiment)
FIG. 4 is an enlarged cross-sectional view of the scattering layer 103 of the light-shielding film 101 according to the second embodiment. The scattering layer 103 is superimposed on at least one surface (here, both surfaces) of the film substrate 2 and scatters incident light. The scattering layer 103 has a resin member 4 arranged along the surface of the film substrate 2 and particles 7 dispersed inside the resin member 4 .

The content of the black component in the scattering layer 103 is set to a value in the range of more than 0% by weight and 4% by weight or less. The scattering layer 103 of the present embodiment contains a black component (black fine particles 5 as an example) here. This black component is dispersed inside the resin member 4 . The particles 7 may be inorganic particles such as silica particles or organic particles such as acrylic particles. When the particles 7 are inorganic particles, the particles 7 are preferably silica particles, and particularly preferably hollow silica particles.

The scattering layer 103 has an uneven surface 103 a formed by the particles 7 . Thereby, the surface 103 a of the scattering layer 103 has the same shape as the surface 3 a of the scattering layer 3 . The scattering layer 103 may not contain a black component as long as it contains the particles 7 to such an extent that the surface 103a is uneven.

Thus, according to the scattering layer 103 , the particles 7 can give the surface of the scattering layer 103 an uneven shape. Therefore, the scattering layer 103 can be provided with good light scattering properties. Moreover, when the black component is contained in the resin member 4 within the above weight range, the resin member 4 can be appropriately colored black by dispersing the black component in the resin member 4 .

When manufacturing the light-shielding film 101 of the second embodiment, a coating liquid similar to that of the first embodiment is prepared except that it contains a predetermined amount of particles 7 . After the coating film 15 is formed on the surface of the film substrate 2 using this coating liquid, the first step S2 and the second step S3 are sequentially performed on the coating film 15 .

Here, in the second embodiment, the transfer step is unnecessary in the first step S2. In the second embodiment, the surface of the coating film 15 becomes uneven immediately after the coating film forming step. Therefore, the surface of the scattering layer 3 can be made uneven by the particles 7 without going through the transfer step (without using the transfer member 8). Thereby, the surface of the coating film 15 can be provided with a light scattering property.

In the second embodiment, the scattering layer 103 is formed by sequentially performing the ultraviolet irradiation step and the second step S3. Incidentally, in the second embodiment, the transfer surface 8a of the transfer member 8 may further impart unevenness to the surface of the coating film 15 by performing the transfer step.

The light-shielding film 101 has a total thickness, an optical density within a wavelength range of 380 nm or more and 780 nm or less, a blackness (L ^* ) that is the lightness specified in JIS Z 8518, and a glossiness of the surface 103a of the scattering layer 103. are set similarly to the light-shielding film 1 of the first embodiment.

Here, L ^* is one of the coordinate axes of the CIE1976 (L ^* , a ^* , b ^* ) color space. The value of L ^* represents the lightness (brightness) of a color and is expressed in 100 levels from 0 to 100. In this scale of 100, 0 is black and 100 is white. The larger the value of L ^* , the brighter the color.

For example, the light-shielding film 101 has a total thickness of 16 μm, an optical density of 6.3 in the wavelength range of 380 nm or more and 780 nm or less, a blackness (L ^* ) of 17.5, and a surface 103a of the scattering layer 103. The glossiness is set to 0.2 at an incident angle of 60 degrees.

The light-shielding film 101 having the scattering layer 103 described above also exhibits the same effect as the light-shielding film 1 . Moreover, the scattering layer 103 of the light-shielding film 101 has the resin member 4 and the particles 7 . Therefore, the particles 7 can give the surface 103a of the scattering layer 103 an uneven shape. Moreover, the light scattering property inside the scattering layer 103 can be improved. Thereby, the scattering layer 103 can be favorably provided with a light scattering property. Further, when the black fine particles 5 are dispersed in the resin member 4 within the above weight range, the resin member 4 can be appropriately colored black.

Also, in the light-shielding film 101, the amount of the black component in the scattering layer 103 is suppressed. Therefore, for example, when the resin member 4 is made of an ultraviolet-curing and electron-beam-curing resin material, it is possible to prevent ultraviolet rays and electron beams from being shielded by the black component. Therefore, the resin material can be cured satisfactorily. As a result, the resin material can be cured even when the amount of the resin material used is small, and the thickness of the scattering layer 103 can be easily reduced.

(confirmation test)
Next, confirmation tests will be described, but the present invention is not limited to the examples shown below.

[Test 1]
As shown in Table 1, Examples 1 and 2, which are the light-shielding films 1 according to the first embodiment, and Example 3, which is the light-shielding film 101 according to the second embodiment, were produced by the following procedure. . Comparative Examples 1 to 3 were produced as comparative examples for Examples 1 to 3.

(Preparation of film substrate)
Film substrates 2 of Examples 1 to 3 were produced by the following procedure. 95% by weight of polyethylene terephthalate and 5% by weight of carbon black (CB-1) produced by the furnace method having an average primary particle size of 18 nm are melt-kneaded in a vented extruder at 280° C. to prepare a CB masterbatch. made. A SiO ₂ masterbatch was prepared by melt-kneading 98.0% by weight of polyethylene terephthalate and 2.0% by weight of silica particles having an average primary particle size of 2.6 μm in a vented extruder at 280°C.

Next, a film raw material was obtained by mixing 13% by weight of the CB masterbatch prepared as described above, 1.5% by weight of the SiO ₂ masterbatch, and 85.5% by weight of PET. This film raw material was extruded into a sheet from a T-shaped die and wound around a mirror surface cooling drum having a surface temperature of 20° C. by an electrostatic casting method to obtain a film intermediate having a thickness of 55 μm.

The film intermediate obtained as described above was sequentially biaxially stretched using a biaxial stretching tester ("FILM STRETCHING TESTER" manufactured by Toyo Seiki Seisakusho Co., Ltd.) as follows. First, the film intermediate was heated to 90° C. and stretched 2.8 times in its longitudinal (extrusion) direction. Next, after cooling the film intermediate, it was further heated to 130° C. and stretched 3.3 times in the lateral direction (film width direction). After that, the film intermediate was heat-treated at 180° C. to obtain film substrates 2 of Examples 1 to 3 having a thickness of 6 μm.

Also, film substrates of Comparative Examples 1 to 3 were prepared as follows. A transparent PET film with a thickness of 6 μm was obtained in the same manner as in Examples 1 to 3, except that the SiO ₂ masterbatch was set to 1.7% by weight and the PET was set to 98.3% by weight to obtain the film raw material. It was produced as a film substrate for Comparative Examples 1 and 3. In addition, “Toyobo Ester Film E5100 #12” manufactured by Toyobo Co., Ltd., which is a commercially available transparent PET film having a thickness of 12 μm, was used as the film substrate of Comparative Example 2.

(Preparation of transfer member)
As the transfer members 8 of Examples 1 and 2, transfer members A and B having the following specifications were prepared. The transfer member A has a thickness of 50 μm, an arithmetic average height Sa of surface roughness of 0.666 μm, a maximum height Sz of surface roughness of 6.177 μm, a total haze of 77.44, and a glossiness at an incident angle of 60 degrees. One having a transfer surface 8a set to 3.3 was prepared. This transfer member A was used in the production of Example 1.

The transfer member B has a thickness of 50 μm, an arithmetic average height of surface roughness Sa of 1.156 μm, a maximum height of surface roughness Sz of 12.483 μm, a total haze of 91.85, and a glossiness at an incident angle of 60 degrees. One having a transfer surface 8a set to 1.3 was prepared. This transfer member B was used in the production of Example 2. Each of the transfer members A and B is made of a film member containing a plurality of resin components and having a phase-separated structure of the plurality of resin components.

(Adjustment of scattering layer)
Coating liquids used in Examples 1 and 2 were prepared as follows. 15% by weight of a black pigment ("MHI Black #273" manufactured by Mikuni Color Co., Ltd., which is a 9% by weight MEK dispersion of carbon black (black fine particles) having an average primary particle size of 150 nm), Resin A, which is an acrylate-containing composition ("HR370" manufactured by Yokohama Rubber Co., Ltd.) 77% by weight, and resin B ("Shiko UV1700B" manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) 8% by weight, which is a polyfunctional methacrylate compound. prepared. This coating liquid contains carbon black, which is a black pigment, at a solid content concentration of 1.08% by weight. By using this coating liquid, the scattering layer 3 of Examples 1 and 2 has a solid concentration of carbon black, which is a black pigment, set to 4% by weight, and a maximum thickness of 4.5 μm.

Moreover, the coating liquid used in Example 3 was prepared as follows. Coating containing 10% by weight of "MHI Black #273" manufactured by Mikuni Color Co., Ltd., 33% by weight of resin A, 4% by weight of resin B, and 53% by weight of particles "Sylysia 448" manufactured by Fuji Silysia Chemical Co., Ltd., each at a solid content ratio prepared the liquid. By using this coating liquid, the scattering layer 103 of Example 3 has a solid content concentration of carbon black, which is a black pigment, set to 4% by weight, and each thickness is set to 3.0 μm.

Moreover, coating liquids used in Comparative Examples 1 and 2 were prepared as follows. A coating liquid containing 64% by weight of "MHI Black #273" manufactured by Mikuni Shiso Co., Ltd., 27% by weight of resin A, and 9% by weight of resin B was prepared. A coating liquid used in Comparative Example 3 was prepared as follows. A coating containing 37% by weight of “MHI Black #273” manufactured by Mikuni Color Co., Ltd., 16% by weight of resin A, 5% by weight of resin B, and 42% by weight of filler particles “Sylysia 448” manufactured by Fuji Silysia Chemical Co., Ltd., each at a solid content ratio. Prepared the solution. By using these coating liquids, the scattering layers of Comparative Examples 1 to 3 have a solid content concentration of carbon black, which is a black pigment, set to 20% by weight.

Next, for Examples 1 and 2, the first step S2 and the first step S2 were performed in the following procedure. Using each coating liquid, a coating film 15 is formed on one surface of the film base material 2 , and a transfer member 8 is superimposed on the coating film 15 . was irradiated with ultraviolet light with an integrated light intensity of 100 mJ/cm ² . After that, a coating film 15 is formed on the other surface of the film substrate 2 in the same manner as described above, and the coating film 15 is transferred via the transfer member 8 in a state in which the transfer member 8 is placed on the coating film 15 . was irradiated with UV light. After that, the intermediate 16 was wound up.

Next, the wound intermediate 16 was unwound again, and in the second step S3, each coating film 15 was irradiated with an electron beam having an accumulated electron dose (absorbed dose) of 250 kGy at once. Thereafter, in the peeling step S4, the transfer member 8 was peeled off from each coating film 15 to obtain the light-shielding films 1 of Examples 1 and 2. Further, a light-shielding film 101 of Example 3 was obtained by the same manufacturing method as that of Examples 1 and 2 except that the coating liquid of Example 3 was used and the transfer step in the first step was omitted. rice field.

In addition, using the film substrates (transparent film substrates) and coating liquids of Comparative Examples 1 to 3, the transparent film substrates and the scattering layers (see Table 2) superimposed on both sides of the transparent film substrates were prepared. As shown, the light-shielding films of Comparative Examples 1 to 3 were prepared. The maximum thickness of each scattering layer in Comparative Examples 1 and 2 was set to 9.5 μm, and the maximum thickness of each scattering layer in Comparative Example 3 was set to 10.0 μm.

The scattering layer provided in the light-shielding films of Comparative Examples 1 to 3 corresponds to the scattering layer 3 provided in Examples 1 to 3, but in that the content of black fine particles is large and has light-shielding properties. , unlike the scattering layer 3, which has a certain degree of optical transparency. The scattering layers of Comparative Examples 1 and 2 have a surface shape formed by containing filler particles. The scattering layer of Comparative Example 3 has a surface shape formed by the transfer surface of the transfer member.

For each light-shielding film of Examples 1-3 and Comparative Examples 1-3, the total thickness of the light-shielding film, the total light transmittance of the film substrate, the thickness of the film substrate, the optical density (OD value), the blackness ( L ^* ), and glossiness at an incident angle of 60 degrees were measured.

The total light transmittance (%) of the film substrate was measured using a haze meter (NDH-5000W manufactured by Nippon Denshoku Co., Ltd.) in accordance with JIS K7136. The optical density (OD value) was measured according to JIS-K 7361 using a transmission densitometer (Model 341C manufactured by Xrite).

The glossiness at an incident angle of 60 degrees was measured according to JlS K7105 using a glossmeter (Model KT-GL0030 manufactured by TQC Therminport Quality Control Co., Ltd.). Blackness (L ^* ) was measured using a UV spectrophotometer (Model U3900H manufactured by Hitachi Ltd.).

Further, the total haze of the transfer members A and B was measured using a Hazemeter (NDH5000W model manufactured by Nippon Denshoku Co., Ltd.). The arithmetic average height Sa and the maximum height Sz of surface roughness were measured using a scanning white light interference microscope (for example, VertScan R3300G manufactured by Ryoka Systems Co., Ltd.). Tables 1 and 2 show the measurement results.

As shown in Tables 1 and 2, all of Examples 1-3 gave better results than Comparative Examples 1-3. It was confirmed that Examples 1-3 had substantially the same optical density (OD value) and blackness as those of Comparative Examples 1-3, but had a smaller total thickness than Comparative Examples 1-3.

Here, in Comparative Examples 1 to 3, it is necessary to ensure the light-shielding property of the scattering layer, and while it contains a relatively large amount of black component, in order to maintain the surface hardness of the scattering layer at a certain level or more, the content of the binder resin is also increased. need to increase. Therefore, it is considered that the maximum thickness of the scattering layer increased and the total thickness of the light-shielding film also increased.

On the other hand, in Examples 1 to 3, since the film substrate 2 is used, there is no such problem regarding the content of the black component and the binder resin, and the maximum thickness of the scattering layer 3 can be reduced. As a result, the total thickness of the light-shielding films 1 of Examples 1 to 3 is well reduced. As a result, in Examples 1 to 3, it is considered that the total thickness of the light-shielding film 1 could be reduced while ensuring good light-shielding properties.

Moreover, it was confirmed that Examples 1 to 3 had a lower glossiness (60 degrees) than Comparative Examples 1 to 3 (especially Comparative Example 1) and had excellent light scattering properties. Further, it was confirmed that the glossiness of Example 2 was significantly lower than that of Example 1.

One of the reasons why such a result was obtained is that the shape of the surface 3a of the scattering layer 3 is formed by the transfer surface 8a of the transfer member 8. It is conceivable that it could be reduced. From the above, the superiority of Examples 1 to 3 over Comparative Examples 1 to 3 was confirmed.

[Test 2]
Next, light-shielding films of Comparative Examples 4 to 9 shown in Tables 3 and 4 below were prepared, and the measurement results thereof were compared with the measurement results of Examples 1 to 3. Comparative Examples 4 to 9 were prepared under the same conditions as in Example 1, except for the differences shown below.

A comparative example 4 having the same structure as that of the example 1 except that a transparent (that is, does not have a light-shielding property) film substrate was used was produced. Further, Comparative Example 5 having the same configuration as Comparative Example 4 except that the content of the black component in the scattering layer was set to 20% by weight and the method of curing the resin of the scattering layer was only ultraviolet curing was produced.

In addition, the content of the black component in the scattering layer is set to 20% by weight, the total light transmittance is set to a value in the range of 70% or more and 100% or less, and each coating that becomes the source of the light shielding layer when making the light shielding film. A comparative example 6 having the same configuration as that of the comparative example 4 was produced except that the integrated electron dose of the electron beam irradiated to the film was set to 250 kGy.

In addition, Comparative Example 7 having the same configuration as Comparative Example 4 except that the content of the black component in the scattering layer was set to 20% by weight and the maximum thickness of each scattering layer was set to 10.0 μm was produced. . In addition, the same configuration as in Comparative Example 4 was used except that the maximum thickness of each scattering layer was set to 8.0 μm, a thermosetting resin was used as the material of the scattering layer, and the resin curing method of the scattering layer was thermosetting. Comparative Example 8 was prepared. Further, the content of the black component in the scattering layer is set to 20% by weight, the maximum thickness of each scattering layer is set to 8.0 μm, a thermosetting resin is used as the material of the scattering layer, and the resin curing method of the scattering layer was heat-cured, and Comparative Example 9 having the same configuration as Comparative Example 4 except that the film substrate was a commercially available transparent PET film “Toyobo Ester Film E5007” manufactured by Toyobo Co., Ltd. was produced.

Here, the scattering layers of Comparative Examples 8 and 9 were produced using the following varnish (coating liquid) containing a thermosetting resin. Specifically, 13.0% by weight of epoxy resin ("YDCN-703" manufactured by Tohto Kasei Co., Ltd.), which is a thermosetting resin, and 11.0% by weight of phenol resin ("XLC-LL" manufactured by Mitsui Chemicals, Inc.). 0% by weight, 34% by weight of "MHI Black #273" manufactured by Mikuni Color Co., Ltd., and 1-cyanoethyl-2-phenylimidazole ("2PZ-CN" manufactured by Shikoku Kasei Co., Ltd.) as a curing accelerator. 025% by weight and 38% by weight of particles "Sylysia 448" manufactured by Fuji Silysia Chemical Co., Ltd. were dissolved in 4% by weight of cyclohexanone as an organic solvent. Next, by mixing this with a bead mill, a varnish having a non-volatile content set to 15% was produced. For Comparative Examples 4-9, the same measurements as Comparative Examples 1-3 were performed. The results are shown in Tables 3 and 4.

As shown in Tables 1, 3, and 4, Comparative Examples 4 to 9 clearly differ from Examples 1 to 3 in that the film substrate does not have a light shielding property. It was found that Comparative Example 4 had lower light-shielding properties than Examples 1 to 3, making it difficult to obtain an appropriate optical density. In addition, in Comparative Example 5, the content of the black component in the scattering layer was slightly increased compared to Comparative Example 4, so that the light-shielding properties were slightly improved, but it was found that it was still difficult to obtain an appropriate optical density. . In addition, the resin of the scattering layer of Comparative Example 5 was insufficiently hardened, and transfer failure of the surface shape of the transfer member A was confirmed.

Further, in Comparative Example 6, since the resin of the scattering layer could not be sufficiently cured by the electron beam, the molding defect of the scattering layer was confirmed. In addition, the transfer member A could not be separated from the scattering layer due to this molding failure, resulting in failure to measure the OD value, blackness (L ^* ), and glossiness. Such uncured resin in the scattering layer and poor molding are caused by the relatively large amount of black component contained in the scattering layer, which prevented sufficient transmission of ultraviolet rays and electron beams from the outside into the inside of the coating film. it is conceivable that.

Moreover, such uncured resin of the scattering layer was also confirmed in Comparative Example 7 in which the maximum thickness of the scattering layer was relatively large. In Comparative Example 8, the resin of the scattering layer was thermally cured, so that the light-shielding film was thermally shrunk during the thermal curing of the resin of the scattering layer, resulting in wrinkles. In Comparative Example 9, the thickness of the film substrate was significantly larger than that of Comparative Example 8, so the occurrence of wrinkles confirmed in Comparative Example 8 was not observed, but the total thickness of the light-shielding film was also significantly increased. I found out. From the above test results, the superiority of Examples 1-3 to Comparative Examples 4-9 was confirmed.

The present invention is not limited to each embodiment, and its configuration and method can be changed, added, or deleted without departing from the scope of the present invention. The black component of the scattering layer may contain at least one of pigments and dyes.

Also, the transfer surface 8a of the transfer member 8 may be formed with unevenness by sandblasting. If the heat shrinkage of the film substrate 2 during the production of the light-shielding film 1 does not pose a significant problem, a thermosetting resin may be used as the precursor of the binder resin 6 . Further, particles 7 may be dispersed inside the resin member 4 of the first embodiment.

In addition, when the resin member 4 is made of a resin material having ultraviolet curable and electron beam curable properties, the content of the black component in the scattering layers 3 and 103 is within an allowable range that does not significantly affect the curing of the resin material. may be set to a value greater than 4% by weight.

As described above, the present invention has an excellent effect of reducing the thickness of a light-shielding film while maintaining good light-shielding properties. Therefore, it is beneficial to widely apply the present invention to a light-shielding film and a method for producing a light-shielding film that can exhibit the significance of this effect.

Reference Signs List 1, 101 light-shielding film 2 film substrate 3, 103 scattering layer 3a, 103a surface of scattering layer 4 resin member 5 black fine particles 7 particles 8 transfer member 8a transfer surface of transfer member

Claims (17)

The content of the black component is set to a value in the range of more than 0% by weight and 4% by weight or less, and a scattering layer that scatters incident light,
The glossiness of at least one surface at an incident angle of 60 degrees is set to a value in the range of 0 to 10,
The optical density in the wavelength range of 380 nm or more and 780 nm or less is set to a value in the range of 4 or more,
A light-shielding film having a total thickness set to a value in the range of 6 μm or more and 26 μm or less. Equipped with a light-shielding film substrate,
The scattering layer is arranged over the film substrate,
2. The light-shielding film according to claim 1, wherein said one surface is the surface of said scattering layer opposite to said film substrate. 3. The light-shielding film according to claim 2, wherein said scattering layer comprises a resin member arranged along the surface of said film substrate and particles dispersed inside said resin member. 4. The light-shielding film according to claim 3, wherein the refractive index of said resin member is set to a value in the range of 1.3 to 1.9. 5. The light-shielding film according to any one of claims 2 to 4, wherein the thickness of the film base is set to a value within the range of 2 µm or more and 12 µm or less. The light shielding according to any one of claims 1 to 5, wherein the blackness (L ^* ), which is the lightness specified in JIS Z 8518, is set to a value in the range of 17.5 or more and 24.0 or less. sex film. The light-shielding film according to any one of claims 1 to 6, wherein the thickness of the scattering layer is set to a value within the range of 3 µm or more and 7 µm or less. The light-shielding film according to any one of claims 1 to 7, wherein the total light transmittance of the scattering layer is set to a value in the range of 70% or more and 100% or less. a preparation step of preparing a coating liquid containing a resin material having ultraviolet curable and electron beam curable properties, and a film substrate having light blocking properties;
a first step of applying the coating liquid to the surface of the film substrate and drying it to form a coating film on the surface, and irradiating the coating film with ultraviolet rays;
and a second step of irradiating the coating film irradiated with the ultraviolet rays with an electron beam,
Through the first step and the second step, the glossiness at an incident angle of 60 degrees on the surface opposite to the film base from the coating film is set to a value in the range of 0 to 10. The film substrate and the scattering layer are provided, the optical density is set to a value in the range of 4 or more in the wavelength range of 380 nm or more and 780 nm or less, and the total thickness is 6 μm or more and 26 μm or less. A method for producing a light-shielding film, which forms a light-shielding film set to a value within the range of In the second step, a transfer member having a transfer surface on which unevenness is formed is arranged such that the transfer surface adheres to the surface of the coating film opposite to the film substrate, and the coating is performed. 10. The method for producing a light-shielding film according to claim 9, wherein the scattering layer having the uneven shape transferred thereto is formed by irradiating the film with an electron beam. In the first step, the coating film is formed on both sides of the film substrate,
In the second step, from one side of the film substrate, the film substrate is irradiated with an electron beam so as to pass through the film substrate, thereby irradiating each of the coating films with the electron beam. 11. The method for producing a light-shielding film according to 9 or 10. 12. Any one of claims 9 to 11, wherein in the preparation step, the coating liquid is prepared so that the content of the black component in the scattering layer is in the range of more than 0% by weight and 4% by weight or less. A method for producing the light-shielding film according to the item. The method for producing a light-shielding film according to any one of claims 9 to 12, wherein the preparation step further prepares the coating liquid containing particles. The light shielding according to any one of claims 9 to 13, wherein in the second step, the scattering layer includes a resin member having a refractive index set to a value in the range of 1.3 to 1.9. A method for producing a flexible film. The method for producing a light-shielding film according to any one of claims 9 to 14, wherein in said preparing step, said film substrate having a thickness set to a value in the range of 2 µm or more and 12 µm or less is prepared. 16. Manufacturing the light-shielding film according to any one of claims 9 to 15, wherein in the second step, the scattering layer having a thickness set to a value in the range of 3 µm or more and 7 µm or less is formed from the coating film. Method. The second step according to any one of claims 9 to 16, wherein the scattering layer having a total light transmittance set to a value in the range of 70% or more and 100% or less is formed from the coating film. A method for producing a light-shielding film.

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