Patterned films and articles

Abstract

To provide a patterned film with a special structure.SOLUTION: A patterned film 2 includes a plurality of portions with different pattern densities. At least one of the portions is porous. Compared to one of the at least one of the porous portions, the other at least one of the portions has a lower pattern density and porosity.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to patterned films. [Background technology]

[0002] Various methods have been reported for forming patterned films, including methods using irradiation with active energy rays such as ultraviolet rays or electron beams, and methods using self-assembling materials such as block copolymers. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-260330 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-197176 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a patterned film having a special structure. [Means for solving the problem]

[0005] According to a first aspect of the present invention, there is provided a patterned film including a plurality of portions having different pattern densities, one or more of which are porous, and one or more of which have a lower pattern density and porosity than one of the porous portions.

[0006] According to a second aspect of the present invention, there is provided an article comprising the patterned film according to the first aspect and a substrate supporting the patterned film. [Effects of the Invention]

[0007] According to the present invention, a patterned film having a special structure is provided. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view schematically illustrating a portion of an article according to a first embodiment of the present invention. [Figure 2] FIG. 3 is a cross-sectional view schematically showing another part of the article according to the first embodiment of the present invention. [Figure 3] FIG. 1 is a cross-sectional view schematically illustrating an example of a state in which a film made of an emulsion is formed on a substrate. [Figure 4] FIG. 10 is a cross-sectional view schematically illustrating an example of a state in which a particulate layer made of a hardened product of dispersed particles is formed in an area irradiated with ultraviolet light by patterned irradiation of ultraviolet light. [Figure 5] FIG. 10 is a cross-sectional view showing an example of a state in which coalescence of dispersed particles occurs in non-irradiated areas by initiating removal of the second liquid from the film. [Figure 6] FIG. 10 is a cross-sectional view schematically illustrating an example of a state in which coalescence of dispersed particles further progresses in a non-irradiated region, and the coalesced dispersed particles penetrate and diffuse into a granular layer made of a hardened product of the dispersed particles. [Figure 7] FIG. 10 is a cross-sectional view schematically illustrating an example of a state in which removal of the second liquid has been completed and the coalesced dispersed particles have completely moved into the granular layer. [Figure 8] FIG. 4 is a cross-sectional view schematically showing an example of a state in which the uncured first liquid is cured by irradiating the entire surface with ultraviolet light. [Figure 9] FIG. 4 is a cross-sectional view schematically illustrating a portion of an article according to a second embodiment of the present invention. [Figure 10] FIG. 6 is a cross-sectional view schematically showing another part of the article according to the second embodiment of the present invention. [Figure 11] FIG. 10 is a cross-sectional view schematically illustrating a portion of an article according to a third embodiment of the present invention. [Figure 12] FIG. 10 is a cross-sectional view schematically showing another part of the article according to the third embodiment of the present invention. [Figure 13] 2 is a graph showing the particle size distribution of the first to third emulsions prepared in the examples. [Figure 14] 10 is a scanning electron microscope photograph showing a cross section of a line and space pattern formed using the first emulsion with varying line and space widths. [Figure 15] 10 is a scanning electron microscope photograph showing a cross section of a line and space pattern formed using the second emulsion with varying line and space widths. [Figure 16] 10 is a scanning electron microscope photograph showing a cross section of a line and space pattern formed using the third emulsion with varying line and space widths. [Figure 17] 16 is a graph showing the concentration distribution obtained by image analysis of a part of the photograph of FIG. 15. [Figure 18] 17 is a graph showing the influence of the ratio of line width to space width on the standard deviation of the concentration distribution obtained by image analysis of the photographs of FIGS. 14 to 16. [Figure 19] 10 is an optical microscope photograph showing the top surface of a line portion of a line and space pattern formed using the first to third emulsions and varying the line width and space width. [Figure 20] 20 is a graph showing the effect of the ratio of line width to space width on the average density obtained by image analysis of the photograph of FIG. 19. [Figure 21] 20 is a graph showing the relationship between the standard deviation of the density distribution obtained by image analysis of the photographs of FIGS. 14 to 16 and the average density value obtained by image analysis of the photograph of FIG. 19. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiments described below are more specific embodiments of any of the above aspects. Elements having the same or similar functions are designated by the same reference numerals, and redundant descriptions will be omitted.

[0010] [First embodiment] Fig. 1 is a cross-sectional view schematically showing a part of an article according to a first embodiment of the present invention, and Fig. 2 is a cross-sectional view schematically showing another part of the article according to the first embodiment of the present invention.

[0011] The article shown in FIGS. 1 and 2 includes a substrate 1 and a patterned film 2. The material and shape of the substrate 1 are not limited. The substrate 1 preferably has a smooth surface. For example, a film or a sheet can be used as the substrate 1.

[0012] The patterned film 2 is supported by a substrate 1. In the example shown in Figures 1 and 2, the patterned film 2 forms a line and space pattern. The patterned film 2 may form a pattern other than a line and space pattern.

[0013] The pattern film 2 includes a plurality of portions with different pattern densities. Here, the term "pattern density" means the ratio of the area of ​​the region where the pattern film 2 is located to the area of ​​the region where the pattern film 2 and its openings are located. For example, when the pattern film 2 forms a line and space pattern, the pattern density of a certain portion is determined by the ratio of the width W of the line portion in this portion to the area of ​​the region where the pattern film 2 is located. L and the width of the space W S Tonowa W L +W S Width of the line part W L Ratio of W L / (W L +W S )

[0014] Among the multiple portions included in the patterned film 2, at least one is porous. FIG. 2 illustrates an example of such a portion. The portion in FIG. 2 has a ratio W L / (W L +W S ) is larger. That is, the portion of FIG. 2 has a higher pattern density compared to the portion of FIG.

[0015] Among the multiple portions included in the patterned film 2, one or more other portions have a lower pattern density and porosity than one of the porous portions. Such portions may be porous or non-porous. Figure 1 illustrates an example of a non-porous portion.

[0016] The pattern film 2 may include three or more portions with different pattern densities. In this case, one or more portions may be porous and two or more portions may be non-porous. Alternatively, two or more portions may be porous and one or more portions may be non-porous. In this case, of these three or more portions, the portion with the lower pattern density preferably has a porosity equal to or less than that of the portion with the higher pattern density. According to one example, the portion with a pattern density of 0.5 or less is non-porous, and the portion with a pattern density of 0.6 or more is porous.

[0017] This porosity correlates with the standard deviation of the concentration distribution obtained by image analysis of the cross section of the patterned film 2. The standard deviation of the concentration distribution obtained by image analysis of the cross section of a portion of the patterned film 2 where the pattern density is 0.6 or more is preferably 5 or more, and more preferably 10 or more.

[0018] The ratio of the maximum to the minimum standard deviations obtained for the portions with different pattern densities is preferably 4.3 or more, more preferably 20.3 or more. When this ratio is small, the difference in porosity is also small. There is no upper limit to this ratio, but it is usually 30.0 or less.

[0019] This image analysis uses the image processing software Image J. Specifically, in each image of the cross section of the patterned film, an area that does not contain areas that would cause contrast noise, such as fractures, is selected. Then, for each selected area, the standard deviation of the density distribution in a 256-level grayscale is extracted as a feature. If the selected area does not have pores (gaps between particles), the standard deviation will be small; the more pores there are, i.e., the higher the porosity, the larger the standard deviation. Therefore, the above ratio serves as an indicator of the porosity ratio.

[0020] The porosity of each portion of the patterned film 2 is also correlated with the light scattering properties of that portion. The porosity of each portion of the patterned film 2 is also correlated with the pattern density of that portion. Therefore, the light scattering properties of each portion of the patterned film 2 are correlated with the pattern density of that portion. Specifically, for multiple portions with different pattern densities, the average value of the concentration distribution obtained by image analysis of their surfaces is positively correlated with the pattern density of those portions. This image analysis is performed using the same method as described above.

[0021] For multiple portions with different pattern densities, the average value of the concentration distribution obtained by image analysis of the surfaces of those portions is positively correlated with the light scattering properties of those portions. The light scattering properties of each portion of the patterned film 2 are positively correlated with the porosity of that portion. Therefore, for multiple portions with different pattern densities, the standard deviation of the concentration distribution obtained by image analysis of the cross sections of those portions is positively correlated with the average value of the concentration distribution obtained by image analysis of those surfaces. This image analysis is performed using the same method as described above.

[0022] The pattern film 2 contains a hardened product 21b1 of dispersed particles, which will be described later, and a polymer phase 21b2.

[0023] The hardened dispersed particles 21b1 form the particulate layer 21b, which is a porous layer.

[0024] The polymerized phase 21b2 is located in the gaps between the particles contained in the particulate layer 21b. In the lower pattern density portion of the patterned film 2, more of these gaps are filled with the polymerized phase 21b2 than in the higher pattern density portion. On the other hand, in the higher pattern density portion of the patterned film 2, more of these gaps remain unfilled with the polymerized phase 21b2 than in the lower pattern density portion. This results in the difference in porosity described above.

[0025] The pattern film 2 is made of, for example, a polymer material. The pattern film 2 is made of, for example, the same material throughout. In one example, the cured material 21b1 and the polymerized phase 21b2 are made of the same polymer material. In this case, the cured material 21b1 and the polymerized phase 21b2 may have the same or different degrees of polymerization. In the latter case, the cured material 21b1 may have a higher degree of polymerization than the polymerized phase 21b2.

[0026] 1 and 2, the polymerized phase 21b2 is not present in the openings of the pattern made of the particulate layer 21b. The polymerized phase 21b2 may be present in the openings of the pattern made of the particulate layer 21b in the form of a layer thinner than the particulate layer 21b.

[0027] This pattern film 2 can be formed, for example, by the method described below (called the Emulsion Transforming Method for Patterning (ET method)). <Preparation of emulsion> First, an emulsion is prepared that contains dispersed particles containing a first liquid that is cured by irradiation with active energy rays, and a dispersion medium that contains a second liquid that is not cured by irradiation with active energy rays.

[0028] The emulsion may be an oil-in-water (O / W) emulsion or a water-in-oil (W / O) emulsion.

[0029] The dispersed particles contain a first liquid that is cured by irradiation with active energy rays. Examples of active energy rays include visible light, ultraviolet rays, electron beams, and X-rays. The first liquid can be, for example, an acrylic monomer or oligomer, a methacrylic monomer or oligomer, an epoxy monomer or oligomer, or a mixture containing one or more of these. Due to advantages such as a wide range of options and a high degree of freedom in adjusting physical properties, it is preferable to use an acrylic monomer or oligomer, or a methacrylic monomer or oligomer as the first liquid. For example, trimethylolpropane triacrylate can be used as the first liquid. The proportion of the monomer and oligomer in the first liquid is, for example, 30 to 100 mass %.

[0030] Furthermore, there are more lipophilic liquids that harden when exposed to active energy rays than hydrophilic ones, so O / W emulsions offer greater freedom in material selection than W / O emulsions.

[0031] The dispersion medium contains a second liquid that does not cure when exposed to actinic radiation. When the first liquid is lipophilic, the second liquid can be a hydrophilic liquid, such as water, a lower alcohol such as methanol or ethanol, or a mixture thereof. On the other hand, when the first liquid is hydrophilic, the second liquid can be a lipophilic liquid, such as an isoparaffinic solvent or mineral spirits.

[0032] The size of the dispersed particles depends on the size of the pattern to be formed, but preferably has an average particle size of 0.5 μm to 0.5 mm. Here, "average particle size" refers to the weight-average diameter obtained by particle size distribution measurement using a laser diffraction / scattering method. If the dispersed particles have this size, the uncured first liquid can efficiently penetrate into the gaps between the particles in a later process.

[0033] The proportion of dispersed particles in the emulsion is preferably 25% by mass or more. When the dispersed particles occupy this proportion in the emulsion, the temperature of the area irradiated with active energy rays can be increased by effectively utilizing the heat of polymerization, thereby destabilizing the dispersion state of the dispersed particles containing the first liquid and simultaneously forming an aggregate layer. The upper limit of the proportion of dispersed particles in the emulsion is not particularly limited, as long as it is within a range that does not cause phase inversion of the emulsion. In one example, this proportion is 70 to 80% by mass or less.

[0034] The first liquid may further contain a photopolymerization initiator. As the photopolymerization initiator, a known photopolymerization initiator, for example, an alkylphenone-based photopolymerization initiator, can be used. An example of the alkylphenone-based photopolymerization initiator is 1-hydroxycyclohexyl phenyl ketone. The first liquid may contain the photopolymerization initiator in an amount of, for example, 0.1 to 10 parts by mass per 100 parts by mass of the total amount of the monomer and oligomer.

[0035] When the emulsion is, for example, an O / W type, the dispersed particles may contain a hydrophobe in addition to the first liquid. Examples of hydrophobes include higher alcohols with low solubility in water, such as cetyl alcohol, hexadecane, polymerizable monomers with relatively high molecular weight hydrocarbon chains, such as lauryl methacrylate and stearyl methacrylate, hydrophobic dyes, and polymers, such as polymethyl methacrylate and polystyrene. The hydrophobe serves to stabilize the emulsion. The hydrophobe can be contained in an amount of, for example, 0.1 to 10 parts by weight per 100 parts by weight of the first liquid.

[0036] The dispersion medium may further contain a surfactant. For example, a commercially available surfactant for emulsion polymerization can be used. For example, a sulfosuccinate surfactant such as dioctyl sodium sulfosuccinate can be used. The emulsion can contain the surfactant in an amount of, for example, 0.1 to 5.0% by mass based on the total mass of the emulsion.

[0037] In the case of O / W emulsions, the dispersion medium generally contains a surfactant to ensure emulsification and the stability of the dispersed particles. Furthermore, O / W emulsions can also contain water-soluble polymers, cellulose nanofibers, etc. in the dispersion medium to improve the long-term storage stability of the emulsion. Furthermore, O / W emulsions can also contain a viscosity modifier or an antifoaming agent in the dispersion medium, as needed.

[0038] On the other hand, in the case of W / O type emulsions, in order to prepare stable emulsions, the dispersion medium can contain a nonionic surfactant or a polymeric dispersion stabilizer having an appropriate hydrophilic-lipophilic balance (HLB) value. If necessary, it is also effective for W / O type emulsions to contain an ionic surfactant in the dispersion medium.

[0039] The emulsion can be prepared by using known emulsification and dispersion techniques, such as a paint shaker, an ultrasonic homogenizer, a colloid mill, a homogenizer, and a membrane emulsification method.

[0040] <Film formation> Next, a film made of the emulsion is formed on a substrate. Hereinafter, the "film made of emulsion" is also referred to as a liquid film. Specifically, the liquid film can be formed on the substrate by applying the emulsion onto the substrate. Any substrate can be used as the substrate, and for example, a film or a sheet can be used.

[0041] The coating method is not particularly limited, and an appropriate coating method such as die coating, comma coating, or curtain coating can be selected depending on the thickness of the liquid film. The thickness of the liquid film can be, for example, 10 to 3000 μm. When a small amount of emulsion is applied to form a liquid film with a small area, a dispenser or the like can be used as needed.

[0042] Fig. 3 shows a schematic diagram of an example of a state in which a film made of an emulsion is formed on a substrate. In Fig. 3, a film 2a made of an emulsion composed of dispersed particles 21a and a dispersion medium 22 is formed on a substrate 1.

[0043] <Irradiation with active energy rays> Next, the formed film is irradiated with active energy rays in a pattern so that the patterned film 2 finally obtained contains a plurality of portions with different pattern densities.

[0044] As described above, examples of the active energy ray include ultraviolet rays, electron beams, X-rays, etc. Pattern irradiation can be carried out, for example, by position-selectively irradiating the active energy ray through a mask or the like, or by position-selectively irradiating the laser beam.

[0045] By irradiating the active energy rays in a pattern, the first liquid contained in the dispersed particles is polymerized and hardened in the region irradiated with the active energy rays (hereinafter also referred to as the irradiated region), thereby forming a granular layer made of the hardened product of the dispersed particles.

[0046] FIG. 4 shows a schematic example of a state in which a particulate layer made of a hardened product of dispersed particles is formed in the area irradiated with ultraviolet light by patterned irradiation of ultraviolet light.

[0047] 4, in the area irradiated with ultraviolet light, the first liquid contained in the dispersed particles 21a is polymerized and hardened, and the dispersed particles 21a become hardened dispersed particle material 21b1. The hardened dispersed particle material 21b1 aggregates and stacks, resulting in the formation of a granular layer 21b made of the hardened dispersed particle material 21b1. The pattern made of this granular layer 21b includes multiple portions with different pattern densities, just like the patterned film 2 that is finally obtained.

[0048] In the region irradiated with ultraviolet light, the second liquid contained in the dispersion medium 22 does not harden, and therefore the dispersion medium 22 exists in the particulate layer 21b, specifically in the gaps between the hardened materials 21b1. On the other hand, in the region not irradiated with ultraviolet light (hereinafter also referred to as the non-irradiated region) in Figure 4, the first liquid contained in the dispersed particles 21a remains unhardened.

[0049] The present inventors believe that the mechanism of aggregation of the cured product 21b1 in the irradiated region is as follows.

[0050] Irradiation with active energy rays causes the dispersed particles 21a to generate heat through polymerization, thereby increasing the temperature of the irradiated area. This temperature increase causes the surfactant that has been adsorbed to the surface of the dispersed particles 21a to stabilize the dispersion of the dispersed particles 21a to desorb. This reduces the surface potential of the dispersed particles 21a as polymerization progresses. As a result, the dispersion of the dispersed particles 21a or their cured product 21b1 becomes unstable, promoting particle aggregation. Furthermore, as the particles aggregate and come into contact with each other, polymerization crosslinking may occur between the particles.

[0051] Furthermore, this aggregation is completed before the surfactant, which has been desorbed by the temperature rise caused by the heat of polymerization, is re-adsorbed onto the particles, so that the aggregated particles maintain their aggregated state without being re-dispersed.

[0052] The aggregation of the cured product 21b1 in the irradiated region may be promoted by adding a crosslinking agent to the dispersion medium in advance, which facilitates crosslinking between particles upon irradiation with active energy rays, thereby promoting particle aggregation.

[0053] <Removal of the second liquid> After irradiation with active energy rays, at least a portion of the second liquid is removed from the film. In this step, it is sufficient to remove at least a portion of the second liquid, but it is also possible to remove all of the second liquid. The second liquid can be removed, for example, by drying the film. Drying is preferably carried out until the amount of the second liquid is 30% by mass or less, more preferably 5% by mass or less, of the amount of the second liquid immediately after forming the liquid film. The second liquid can be removed by leaving the film at room temperature, but is preferably removed by heating and drying the film. Heat drying can be carried out, for example, by heating the film at a temperature in the range of 40 to 100°C for 0.1 to 1 hour. By removing the second liquid, at least a portion of the uncured first liquid can be transferred from the area not irradiated with active energy rays to the granular layer consisting of the cured product of the dispersed particles.

[0054] In this step, the removal of the second liquid causes at least a portion of the uncured first liquid to migrate from the non-irradiated region to the granular layer made of the cured product of the dispersed particles. The migration of the uncured first liquid from the non-irradiated region to the granular layer may be carried out so that all of it migrates to the granular layer, or so that only a portion of it migrates to the granular layer.

[0055] In this method, it is not necessary to carry out a development step after irradiation with active energy rays, that is, to remove the uncured first liquid using a developer.

[0056] Figures 5 to 7 schematically show an example of changes in the state of the film caused by the removal of the second liquid. Figure 5 schematically shows an example of a state in which coalescence of dispersed particles occurs in non-irradiated areas as the removal of the second liquid from the film begins. Figure 6 schematically shows an example of a state in which coalescence of dispersed particles further progresses in non-irradiated areas, and the coalesced dispersed particles penetrate and diffuse into the granular layer made of the hardened dispersed particles. Figure 7 schematically shows an example of a state in which removal of the second liquid is complete and the coalesced dispersed particles have completely migrated into the granular layer.

[0057] When a portion of the second liquid contained in the dispersion medium 22 is removed from the film 2a, the second liquid filling the gaps between particles in the granular layer 21b decreases in the irradiated region, as shown in Fig. 5, while the second liquid decreases in the non-irradiated region, and the dispersed particles 21a coalesce to form coalesced particles 21a'. Then, as shown in Fig. 6, the uncured first liquid forming the coalesced particles 21a' penetrates into the gaps in the granular layer 21b and diffuses into the granular layer 21b. This penetration and diffusion is thought to occur due to capillary force.

[0058] When the removal of the second liquid is complete, the migration of the uncured first liquid from the non-irradiated area to the granular layer 21b is also complete. As a result, for example, the structure shown in Figure 7 is obtained. Note that when the second liquid is completely removed from the film, the only liquid remaining in the film is, for example, the liquid constituting the dispersed particles 21a or their coalescence 21a'.

[0059] As described above, the pattern formed by the granular layer 21b includes a plurality of portions with different pattern densities, similar to the final pattern film 2. As will be explained below, the amount of the first liquid that penetrates into gaps in the granular layer 21b differs between portions with lower pattern density and portions with higher pattern density.

[0060] That is, there is a larger non-irradiated area around the area with a lower pattern density, and therefore a larger amount of the first liquid, whereas there is a smaller non-irradiated area around the area with a higher pattern density, and therefore a smaller amount of the first liquid.

[0061] As a result, in the areas where the pattern density is lower, a larger amount of the first liquid penetrates into the gaps in the granular layer 21b, for example, the entire gaps are filled with the first liquid.

[0062] On the other hand, in areas where the pattern density is higher, a smaller amount of the first liquid penetrates into the gaps in the granular layer 21b, for example, only a portion of the gaps is filled with the first liquid.

[0063] <Establishing the pattern> Finally, the uncured first liquid contained in the film from which the second liquid has been removed is cured. The uncured first liquid can be cured, for example, by irradiating the entire film with active energy rays. This forms a patterned film.

[0064] FIG. 8 shows a schematic diagram of an example of the state in which the uncured first liquid is cured by irradiating the entire surface with ultraviolet light. As shown in FIG. 8, when the entire film is irradiated with ultraviolet light, the uncured first liquid is cured by polymerization. As a result, a polymerized phase 21b2 is formed. Furthermore, in the cured material 21b1 constituting the particulate layer 21b, further polymerization proceeds due to the ultraviolet light irradiation. As a result, a patterned film 2 consisting of the cured material 21b1 of the dispersed particles and the polymerized phase 21b2 is formed.

[0065] As described above, before the entire surface is irradiated with ultraviolet light, in the granular layer 21b, the gaps in the lower pattern density portions are entirely filled with the first liquid, while in the higher pattern density portions, only some of the gaps are filled with the first liquid. Therefore, in the patterned film 2 obtained by irradiating the entire surface with ultraviolet light, the higher pattern density portions have a higher porosity than the lower pattern density portions.

[0066] As described above, the uncured first liquid can be cured after all of the uncured first liquid present in the non-irradiated region has migrated from this region to the granular layer. Alternatively, the uncured first liquid can be cured when only a portion of the uncured first liquid present in the non-irradiated region has migrated from this region to the granular layer. For example, the entire film can be irradiated with active energy rays before the second liquid is completely removed from the film (i.e., at a stage in the middle of the first liquid in the non-irradiated region penetrating and diffusing into the granular layer), such as the stage shown in Figure 6. This allows for a patterned film to be obtained in which the non-irradiated region has a thickness and the irradiated region is thicker than the non-irradiated region.

[0067] <Effects> As described above, the patterned film 2 includes multiple portions with different pattern densities. Of these multiple portions, one or more are porous, and the other one or more have lower pattern densities and porosities. Therefore, in an article including the patterned film 2, the areas corresponding to the portions with higher pattern densities have higher light scattering properties than the areas corresponding to the portions with lower pattern densities. Therefore, this article can display, for example, images or patterns by utilizing the difference in light scattering properties.

[0068] Furthermore, this patterned film 2 can be formed in a self-organizing manner by simply irradiating the emulsion film with active energy rays in a pattern and then removing the second liquid. This method does not require a guide pattern to be provided on the substrate in advance, nor does it require a development process. Therefore, this patterned film 2 can be produced by a simple method.

[0069] Furthermore, while conventional techniques have only been able to achieve pattern sizes of, for example, a line width of several nanometers to several hundred micrometers and a height difference of several nanometers to several hundred micrometers, the above method can achieve a wide range of pattern sizes. For example, the above method can form a pattern film with a large line width or height difference, for example, a line width on the order of micrometers to millimeters and a height difference on the order of micrometers to millimeters. In one example, the above method can form a pattern film with a line width in the range of 10 micrometers to 5 mm and a height difference in the range of 10 micrometers to 2 mm.

[0070] Furthermore, the above method has excellent control over the shape and size of the pattern, making it possible to form patterned films of various shapes and sizes.

[0071] [Second embodiment] Fig. 9 is a cross-sectional view schematically showing a part of an article according to a second embodiment of the present invention, and Fig. 10 is a cross-sectional view schematically showing another part of an article according to the second embodiment of the present invention.

[0072] The article according to the second embodiment is similar to the article according to the first embodiment, except for the following points. That is, the article according to the second embodiment further includes a layer 3 attached to the substrate 1 with the patterned film 2 sandwiched therebetween, as shown in FIGS. 9 and 10 . The layer 3 may have a single-layer structure or a multi-layer structure. According to one example, the layer 3 serves as a protective layer that protects the patterned film 2 from damage.

[0073] The layer 3 is attached to the substrate 1 and the patterned film 2 by an adhesive layer 4. The adhesive layer 4 is made of an adhesive or a pressure-sensitive adhesive. The adhesive layer 4 fills the gaps in the patterned film 2. Typically, the adhesive layer 4 has a different refractive index from the patterned film 2, so this article also exhibits the same optical effect as the article according to the first embodiment.

[0074] The adhesive layer 4 does not have to fill the gaps in the patterned film 2. An article having such a structure also exhibits the same optical effects as the article according to the first embodiment.

[0075] Furthermore, in this article, the ease of peeling of layer 3 may differ between positions corresponding to areas with higher pattern density and positions corresponding to areas with lower pattern density. For example, the adhesive strength to layer 3 may differ between the areas with higher pattern density and the areas with lower pattern density due to differences in their structures. Furthermore, the ease of brittle fracture may differ between the areas with higher pattern density and the areas with lower pattern density due to differences in their structures. Therefore, this article can also be used, for example, as a brittle label, in which one of the layers undergoes brittle fracture when an attempt is made to peel it from another article to which it is attached.

[0076] Instead of attaching the layer 3 via the adhesive layer 4, a coating liquid may be applied onto the substrate 1 and the pattern film 2, and the coating may be cured. The layer obtained in this manner may also be used, for example, as a protective layer.

[0077] [Third embodiment] Fig. 11 is a cross-sectional view schematically showing a part of an article according to a third embodiment of the present invention, and Fig. 12 is a cross-sectional view schematically showing another part of an article according to the third embodiment of the present invention.

[0078] The article according to the third embodiment is similar to the article according to the first embodiment except for the following points: As shown in Figures 11 and 12, the article according to the third embodiment further includes a color material 5 carried on the patterned film 2. The color material 5 is, for example, a dye, a pigment, or a combination thereof.

[0079] In the pattern film 2, portions with higher pattern density carry a larger amount of color material 5 than portions with lower pattern density. Therefore, in this article, areas corresponding to the higher pattern density are more intensely colored than areas corresponding to the lower pattern density. Therefore, this article can display, for example, a colored image or a colored pattern such as a wood grain pattern. The surface of the substrate 1 may or may not carry a color material 5.

[0080] This article is produced, for example, by the following method. First, an article according to the first embodiment is manufactured. Next, a colorant 5 is supplied to this article, and excess colorant 5 is removed. Alternatively, a solution or dispersion containing the colorant 5 is supplied to this article, and the solvent or dispersion medium is removed.

[0081] As described above, the portions of the patterned film 2 with higher pattern densities have higher porosity than the portions with lower pattern densities. Therefore, the former have higher adsorption capacity than the latter. Therefore, this method can produce an article in which the portions with higher pattern densities and the portions with lower pattern densities carry different amounts of colorant 5.

[0082] [Fourth embodiment] The coloring method described in the third embodiment can also be applied to security technology, for example, as will be described below.

[0083] In the article according to the first embodiment, the regions corresponding to the higher pattern density have higher light scattering properties than the regions corresponding to the lower pattern density. Therefore, when the substrate 1 is colored, the regions corresponding to the higher pattern density appear white, for example, while the regions corresponding to the lower pattern density appear the color of the substrate 1 or a color close to it, and the regions corresponding to the openings in the pattern film 2 appear the color of the substrate 1. Furthermore, when the substrate 1 is colorless and transparent and the background of the article is colored, the regions corresponding to the higher pattern density appear white, for example, while the regions corresponding to the lower pattern density appear the color of the background or a color close to it, and the regions corresponding to the openings in the pattern film 2 appear the color of the background.

[0084] In contrast, when the substrate 1 is white, or when the substrate 1 is colorless and transparent and has a white background, the areas corresponding to the higher pattern density, the areas corresponding to the lower pattern density, and the areas corresponding to the openings in the pattern film 2 all appear white. That is, in this case, the pattern film 2 forms a latent image that is visualized by coloring it using the method described in the third embodiment. Therefore, when this article is used as a security element on which a latent image is recorded, the latent image is visualized using the coloring method described in the third embodiment, and authenticity can be determined by confirming this visualized image. [Example]

[0085] <Preparation of first emulsion> An O / W emulsion was prepared using the following ingredients: Monomer or oligomer: trimethylolpropane triacrylate (Light Acrylate (registered trademark) TMP-A, manufactured by Kyoeisha Chemical Co., Ltd.) Photopolymerization initiator: 1-benzoylcyclohexanol (Lunacure® 200, commercially available from DKSH Japan) Surfactant: Dioctyl sodium sulfosuccinate (Sunmorin (registered trademark) OT-70, manufactured by Sanyo Chemical Industries, Ltd.) Second liquid: distilled water First, 0.375 g of Lunacure® 200, 0.259 g of Sunmorin® OT-70, and 7.5 g of Light Acrylate® TMP-A were placed in a 50 mL brown vial, in that order, and subjected to a rotary mixing process on a ball mill roll. Next, 9 g of distilled water was added to the vial, and the mixture was subjected to an emulsification / dispersion process. The emulsification / dispersion process was carried out by propeller stirring. The propeller rotation speed was 738 rpm, and the stirring time was 10 minutes. The vial was then subjected to rotary mixing for 2 hours. In this manner, a first emulsion was prepared.

[0086] <Preparation of Second Emulsion> The second emulsion was prepared in the same manner as described above for the first emulsion, except that the emulsification and dispersion treatment was carried out using a paint shaker (Asada Iron Works PC1171). Shaking with the paint shaker was carried out for 30 seconds.

[0087] <Preparation of the third emulsion> The third emulsion was prepared in the same manner as described above for the first emulsion, except that the emulsification and dispersion process was carried out by hand shaking, which was carried out 10 times.

[0088] <Measurement of particle size distribution> The particle size distribution and average particle size of each of the first to third emulsions were measured. For these measurements, a measurement system consisting of a Nikkiso Microtrac MT3300EXII particle size distribution analyzer equipped with a Nikkiso Microtrac USVR liquid circulation pump was used, and the weight-average diameter was determined as the average particle size. The resulting emulsions consisted of dispersed particles (hereinafter also referred to as emulsion droplets) containing the first liquid and a dispersion medium containing the second liquid. The average particle sizes of the first to third emulsions are summarized in Table 1 below. The particle size distributions of the first to third emulsions are shown in Figure 13.

[0089] [Table 1]

[0090] <Film formation> Using each of the first to third emulsions, multiple films were formed by the following method. First, five layers of 20 mm wide, 80 μm thick masking tape (manufactured by 3M) were attached to the surface of a microscope slide. The center of this five-layer laminate was cut out into a rectangular shape, thereby creating a cell (hereinafter referred to as a liquid-reservoir cell) with a depth of 400 μm and an opening measuring 10 mm × 30 mm.

[0091] Next, 112 μL of emulsion was collected using a micropipette and spread and filled into a liquid storage cell, forming a membrane (i.e., liquid membrane) made of emulsion with a thickness of approximately 375 μm, calculated taking into account the specific gravity.

[0092] <UV irradiation> A 0.25 mm thick copper mask with stripe-shaped openings was placed on the liquid film via a 1 mm thick aluminum spacer so as not to come into contact with the liquid surface. Here, multiple copper masks were used, each with stripe-shaped openings corresponding to the line and space pattern and with different widths of the line and space portions.

[0093] Next, a UV parallel light exposure machine (SAN-EI ELECTRONIC UVC-2502S) was used to expose the film at an illuminance of 4.6 mW / cm. 2 By irradiating the mask with ultraviolet light for 8 seconds, the cumulative light intensity on each liquid film was 36.8 mJ / cm 2 As a result, the first liquid was polymerized in the area irradiated with ultraviolet light, and a particulate layer made of a cured product of the dispersed particles was formed.

[0094] <Drying the film> Next, the film after UV exposure was air-dried at room temperature (22°C, 49% RH) for 90 minutes, thereby removing water from the film.

[0095] <Establishing the pattern> Finally, the cumulative light dose for the dried film was 414 mJ / cm 2 (=4.6mW / cm 2 The entire surface was exposed to ultraviolet light for 10 seconds (×90 seconds). This allowed the pattern to be fixed. In this way, a patterned film was formed.

[0096] <Imaging the surface of a patterned film> The surface of each patterned film was photographed using a digital camera (HOZAN L-835) equipped with a zoom lens (HOZAN L-815). Some of the images obtained in this manner are shown in Figure 19. Photographs of the patterned films were taken by placing a piece of black paper behind the slide glass on which the pattern was formed.

[0097] <Imaging the cross section of a patterned film> First, each patterned film was peeled off from the slide glass using tweezers. Next, each patterned film was folded to create a fracture surface. For highly porous and brittle patterned films, a cross section was created using a razor. Next, each patterned film with a cross section was fixed to a sample stage for cross-section observation with double-sided carbon conductive tape, and gold was sputtered onto the tape. In this way, samples for observation with a scanning electron microscope (SEM) were prepared. Then, the cross sections of each sample were photographed using the SEM. The images obtained in this manner are shown in Figures 14 to 16.

[0098] Fig. 14 is a scanning electron microscope photograph showing a cross section of a line and space pattern formed using the first emulsion with varying line and space widths. Fig. 15 is a scanning electron microscope photograph showing a cross section of a line and space pattern formed using the second emulsion with varying line and space widths. Fig. 16 is a scanning electron microscope photograph showing a cross section of a line and space pattern formed using the third emulsion with varying line and space widths.

[0099] <Image analysis> Image analysis was performed using the image processing software Image J. Specifically, in each image of the cross section of the patterned film, an area that did not contain areas that would cause contrast noise, such as fractures, was selected. Then, for each selected area, the standard deviation of the density distribution in a 256-level grayscale was extracted as a feature. Note that if there are no pores (gaps between particles) in the selected area, the standard deviation will be small, and the more pores there are, i.e., the higher the porosity, the larger the standard deviation will be.

[0100] The standard deviation of the density distribution in the 256-level gray scale was also determined for each image of the pattern film surface using the same method as above. Furthermore, the average density was calculated from this density distribution and used as an index of the whiteness of the pattern film surface.

[0101] <Result 1> 14 to 16, the patterned film becomes porous when the line width to space width ratio (L / S ratio) is 1 to 1.5 or more, and this tendency does not depend on the average particle size of the emulsion.

[0102] Figure 17 shows the density distribution obtained by image analysis of a portion of the photograph in Figure 15. As shown in Figure 17, when the ratio of line width to space width is small (L / S ratio = 1), the density, i.e., brightness, of the image of the cross section of the patterned film is distributed over a relatively narrow range. In contrast, when the ratio of line width to space width is large (L / S ratio = 3), the density of the image of the cross section of the patterned film is distributed over a relatively wide range.

[0103] Table 2 shows the standard deviation of the concentration distribution obtained by image analysis of the photographs in Figures 14 to 16. Also, Figure 18 shows the effect of the ratio of line width to space width on the standard deviation of the concentration distribution obtained by image analysis of the photographs in Figures 14 to 16.

[0104] [Table 2]

[0105] As shown in Table 2 and Figure 18, regardless of which emulsion was used, the larger the line width to space width (L / S ratio), the larger the standard deviation of the density distribution obtained for the image of the cross section of the patterned film. Also, the smaller the average particle size of the emulsion, the greater the effect of the L / S ratio on the standard deviation.

[0106] 14 to 16 and 18, it can be seen that there is a positive correlation between the porosity of the patterned film and the standard deviation of the concentration distribution obtained from the image of the cross section of the patterned film. From the above, it can be seen that the standard deviation of the concentration distribution obtained from the image of the cross section of the patterned film can be an indirect index of the porosity of the patterned film.

[0107] <Result 2> Table 3 shows the average density values ​​obtained by image analysis of the photograph in Figure 19. Also, Figure 20 shows the effect of the ratio of line width to space width on the average density values ​​obtained by image analysis of the photograph in Figure 19.

[0108] [Table 3]

[0109] As shown in Table 3 and Figure 20, regardless of which of the first to third emulsions was used, the larger the line width to space width (L / S ratio), the higher the average density obtained for the image of the patterned film surface. That is, the larger the L / S ratio, the higher the light scattering property of the patterned film. Furthermore, the smaller the average particle size of the emulsion, the higher the average density obtained for the image of the patterned film surface.

[0110] 19 and 20, it can be seen that there is a positive correlation between the whiteness of the pattern film and the average value of the density obtained from the image of the pattern film surface.

[0111] Tables 4 to 6 show the standard deviations of the concentration distributions obtained by image analysis of the photographs in Figures 14 to 16, and the average values ​​of the concentrations obtained by image analysis of the photograph in Figure 19. Also, Figure 21 shows the relationship between the standard deviations of the concentration distributions obtained by image analysis of the photographs in Figures 14 to 16, and the average values ​​of the concentrations obtained by image analysis of the photograph in Figure 19.

[0112] [Table 4]

[0113] [Table 5]

[0114] [Table 6]

[0115] As shown in Tables 4 to 6 and FIG. 21, there is a positive correlation between the standard deviation of the density distribution obtained from the image of the cross section of the patterned film and the average density obtained from the image of the surface of the patterned film. The invention as originally claimed is set forth below. [1] A patterned film comprising a plurality of portions with different pattern densities, one or more of which are porous, and one or more of which have a lower pattern density and porosity compared to one of the one or more porous portions. [2] Item 2. The patterned film according to item 1, wherein among the plurality of portions, portions with lower pattern density have a porosity equal to or lower than that of portions with higher pattern density. [3] Item 3. The patterned film according to Item 1 or 2, wherein one or more of the plurality of portions is non-porous. [4] Item 4. The patterned film according to any one of items 1 to 3, wherein the line width is in the range of 10 μm to 5 mm. [5] Item 5. The patterned film according to any one of items 1 to 4, wherein the height difference is within a range of 10 μm to 2 mm. [6] Item 6. An article comprising the patterned film according to any one of items 1 to 5 and a substrate supporting the patterned film. [7] Item 7. The article according to item 6, further comprising layers attached to the substrate with the patterned film sandwiched therebetween. [8] Item 8. The article according to item 6 or 7, further comprising a colorant carried on the patterned film. [Explanation of symbols]

[0116] 1...substrate, 2...patterned film, 2a...film made of emulsion, 3...layer, 4...adhesive layer, 5...colorant, 21a...dispersed particles, 21a'...combined, 21b...granular layer, 21b1...cured product of dispersed particles, 21b2...polymerized phase, 22...dispersion medium

Claims

1. A patterned film comprising a plurality of portions with different pattern densities, one or more of the plurality of portions being porous, and one or more of the other portions having a lower pattern density and porosity compared to one of the one or more porous portions.

2. The patterned film of claim 1 , wherein one or more of the plurality of portions is non-porous.

3. 3. The patterned film according to claim 1, wherein the line width is in the range of 10 [mu]m to 5 mm.

4. 4. The patterned film according to claim 1, wherein the height difference is in the range of 10 μm to 2 mm.

5. An article comprising the patterned film according to any one of claims 1 to 4 and a substrate supporting the patterned film.

6. 6. The article of claim 5, further comprising a layer attached to the substrate with the patterned film sandwiched therebetween.

7. The article according to claim 5 or 6, further comprising a colorant carried on the patterned film.

Images