JP2012118321A - Reflection type color film substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transparent film coloring without using a conventional coloring material such as pigment, coloring matter and dye and being transparent and also to provide a reflection type color film substrate excellent in performance which uses the above-mentioned transparent film.SOLUTION: The transparent film of the present invention is a transparent film containing a transparent resin and spherical particles and characterized in that the spherical particles are dispersed in the transparent film where the average particle diameter is 50 to 200 nm. In addition, the substrate for an electronic component of the present invention is characterized by comprising the above-described transparent film.

Description

The present invention relates to a reflective color film substrate.

Conventionally, in order to color a resin film, it has been essential to contain a coloring pigment, a coloring matter, a dye, and the like. However, if a pigment having a large particle size is used, the film becomes opaque. On the other hand, even when a nano-scale particle size is used, the film often becomes opaque because the particles aggregate. Furthermore, pigments, dyes, and the like are inferior in heat resistance, and change with time may be a problem.

Then, as a method other than coloring by absorbing a part of light such as pigments, pigments, dyes, etc., optical color bodies utilizing the structural color development of colloidal microcrystals of spherical nanoparticles are disclosed (for example, , See Patent Document 1). However, a transparent film showing structural color development while maintaining transparency has not been obtained.

JP 2007-182392 A

An object of the present invention is to provide a transparent film that is colored and transparent without using conventional colorants such as pigments, pigments, and dyes.
Another object of the present invention is to provide a reflective color film substrate excellent in performance using the above-described transparent film.

Such an object is achieved by the present invention described in the following (1) to (8).
(1) A transparent film containing a transparent resin and spherical particles,
A transparent film, wherein the spherical particles have an average particle diameter of 40 to 200 nm and are dispersed in the transparent film.
(2) The relationship between the average particle diameter of the spherical particles dispersed in the transparent film and the interparticle distance is
(1) Transparent film having an average particle diameter of 40 to 60 nm and an interparticle distance of 120 to 180 nm (2) Transparent film having an average particle diameter of 70 to 90 nm and an interparticle distance of 210 to 270 nm (3) Average particle diameter of 100 to The transparent film of (1), which is a laminated film obtained by laminating at least two of three transparent films of a transparent film having a thickness of 120 nm and an interparticle distance of 300 to 360 nm.
(3) The transparent film according to (1) or (2), wherein the content of the spherical particles is 5 to 80% by volume of the entire transparent film.
(4) The transparent film according to any one of (1) to (3), wherein an average inter-particle distance of the spherical particles dispersed in the transparent film is 120 to 360 nm.
(5) The transparent film according to any one of (1) to (4), wherein the transparent resin is one of an epoxy resin and an acrylic resin.
(6) The transparent film according to any one of (1) to (5), wherein the spherical particles are metal oxide particles containing silicon.
(7) The transparent film according to any one of (1) to (6), wherein a difference in refractive index between the transparent resin and the spherical particles is 0.1 or less.
(8) A reflective color film substrate comprising the transparent film according to any one of (1) to (7).

According to the present invention, it is possible to obtain a transparent transparent film that develops color without using conventional colorants such as pigments, pigments, and dyes.
In addition, according to the present invention, a reflective color film substrate having excellent performance can be obtained.

It is a chart which shows the data of the small angle X-ray scattering measurement of a transparent sheet.

Hereinafter, the transparent film and reflective color film substrate of the present invention will be described.
The transparent film of the present invention is a transparent film containing a transparent resin and spherical particles, wherein the spherical particles are dispersed in the transparent film with an average particle diameter of 40 to 120 nm.
In addition, the reflective color film substrate of the present invention is formed of the transparent film described above.

(Transparent film)
First, the transparent film will be described.
The transparent resin film of the present invention is a transparent film containing a transparent resin and spherical particles, wherein the spherical particles are dispersed with an average particle diameter of 40 to 200 nm in the transparent film. . As a result, spherical particles can select light of a specific wavelength under light irradiation to form a structural color, and the spherical particles are excellent in transparency because they are dispersed microscopically as described above. It is.
As described above, the reason why the spherical particles can select the light of a specific wavelength and form the structure is considered as follows.
By fixing (arranging) the spherical particles in the resin without agglomeration, the spherical particles can form a regular array structure in the transparent film, thereby selectively reflecting only a specific wavelength. Thus, light of that wavelength can be colored.

Here, the structural coloration is a phenomenon in which light is scattered due to a regularly arranged three-dimensional structure, also called a structural color. The determination of whether or not structural color development is exhibited can be carried out quantitatively as follows. Observation of a light transmittance in the wavelength region of the color of the structural color in the light transmittance of the wavelength dispersion of the transparent film, a unimodal peak having a reflectance of 30% or more, preferably 40% or more in the light transmittance of 300 to 500 nm If so, it is determined that a blue structural color is exhibited. In the case of green, a light transmittance of 500 to 600 nm is observed, and in the case of red, a reflectance of 30% or more, preferably 40% or more, is observed at a light transmittance of 550 to 700 nm. The structural color development is shown.

The average particle diameter of the spherical particles dispersed in the transparent film is particularly preferably 10 to 200 nm, and most preferably 120 to 160 nm. When the average particle diameter is within the above range, the balance between transparency and color developability is particularly excellent.
The average particle diameter of the spherical particles in such a transparent film can be evaluated by, for example, small-angle X-ray scattering using high-intensity radiation light.

Specifically, films having blue, green and red structural colors can be produced at the following average particle diameter and interparticle distance, respectively.
(1) Transparent structural color film with blue color having an average particle size of 40 to 60 nm and an interparticle distance of 120 to 180 nm (2) Green structural color with an average particle size of 70 to 90 nm and an interparticle distance of 210 to 270 nm Transparent film (3) Transparent film that develops a red color structure with an average particle size of 100 to 120 nm and a distance between particles of 300 to 360 nm

Each of the films can be produced as a transparent film that produces a light-colored structural color. In principle, it is difficult to produce a transparent film that produces multiple types of structural colors with a single film.

It is also possible to produce a transparent film capable of multicolored color by producing films that structurally develop the three primary colors of light, blue, green, and red, respectively, and then laminating them.
As a method for laminating the films, a method in which the respective films are stacked and pressure-bonded is preferable. There are thermocompression bonding and ultrasonic pressure bonding methods as the pressure bonding method. It is also possible to apply an adhesive to the bonding surface of the film and laminate them by adhesion. Since the film needs to be light transmissive, lamination by pressure bonding without using an adhesive is the most preferred lamination method.

Examples of the transparent resin include alicyclic polymers, polyacrylates, polymethacrylates, cycloolefin polymers, and epoxy polymers.
Moreover, the resin composition containing the transparent resin mentioned above, a hardening | curing agent, etc. may be sufficient. Specifically, among these, a resin composition containing a resin having transparency such as an alicyclic polymer and polyacrylate is preferable. Specifically, what is obtained by curing and crosslinking a resin composition containing a compound having two or more functional groups with heat, light or the like is preferable.

Examples of the compound having two or more functional groups include acrylic resins such as (meth) acrylates, epoxy resins such as glycidyl type epoxy resins, oxetane compounds, compounds having oxetanyl groups, and vinyl ether compounds. Among these, either one of epoxy resin and acrylic is preferable. Thereby, crosslinking reactivity can be improved.

Examples of glycidyl type epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, naphthalene type epoxy resins or hydrogenated products thereof, epoxy resins having a dicyclopentadiene skeleton, and triglycidyl isocyanurate. Examples include epoxy resins having a skeleton, epoxy resins having a cardo skeleton, and epoxy resins having a polysiloxane structure. Examples of the alicyclic epoxy resins include 3,4-epoxycyclohexylmethyl 3 ′, 4′-epoxycyclohexanecarboxylate, 3,4-epoxycyclohexylmethanol and 3,4-epoxycyclohexanecarboxylic acid are ester-bonded to both ends of 1,2,8,9-diepoxylimonene and ε-caprolactone oligomer, respectively. And an alicyclic epoxy resin having a hydrogenated biphenyl skeleton and a hydrogenated bisphenol A skeleton. Etc.) are preferably used.

Among these, (meth) acrylates having an alicyclic structure and two or more functional groups are preferred in terms of heat resistance and linear expansion coefficient. Furthermore, it is not particularly limited as long as it is a (meth) acrylate having two or more functional groups including an alicyclic structure, but is selected from the following chemical formula (1) and chemical formula (2) from the viewpoint of heat resistance and transparency. Further, at least one (meth) acrylate is preferred.

Among the (meth) acrylates represented by the formulas (1) and (2), at least one acrylate selected from the formulas (1) and (2) is preferable from the viewpoint of reactivity and thermal stability. More preferably, dicyclopentadienyl diacrylate having a structure in which R ¹ and R ² are hydrogen, a is 1 and b is 0 in the general formula (1), and in the general formula (2), X is Perhydro-1,4; 5,8-dimethananaphthalene-2,3,7- (oxymethyl) tri having a structure in which —CH ₂ OCOCH═CH ₂ , R ³ , R ⁴ are hydrogen and p is 1 The acrylate, X, R ³ and R ⁴ are all hydrogen and at least one acrylate selected from acrylates having a structure in which p is 0 or 1, and most preferably in view of viscosity and the like, X, in R ^3, R ⁴ are all hydrogen p is norbornane dimethylol diacrylate having a structure which is 0. The (meth) acrylate represented by the formula (2) can be obtained by a known method disclosed in JP-A-5-70523.

The resin composition containing the compound having two or more functional groups contains a monofunctional compound within a range that does not extremely impair the required properties for the purpose of imparting flexibility. Can do.

The content of the transparent resin in the transparent film is preferably 50 to 70% by volume, and particularly preferably 50 to 60% by volume of the entire transparent film. When the content is within the above range, the transparency is particularly excellent.

When the resin composition is cured by active energy rays such as ultraviolet rays, it is preferable to include a photopolymerization initiator that generates radicals, cations, and the like in the resin composition. As the photopolymerization initiator used in that case, for example, as a radical generator, benzophenone, benzoin methyl ether, benzoin propyl ether, diethoxyacetophenone, 1-hydroxy-cyclohexyl-phenyl ketone, 2,6-dimethylbenzoyl diphenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide is exemplified, and examples of the cation generator include aromatic sulfonium salts and aromatic iodonium salts. Two or more of these photopolymerization initiators may be used in combination.

The content of the photopolymerization initiator in the resin composition may be an appropriate amount to be cured, and is 0.01 to 2 parts by weight with respect to 100 parts by weight of the organic component containing the functional group in the resin composition. Is more preferably 0.02-1 part by weight, and most preferably 0.1-0.5 part by weight. When the amount of the photopolymerization initiator added is too large, the polymerization proceeds rapidly, and problems such as increased birefringence, coloring, and cracks during curing occur. On the other hand, if the amount is too small, the composition cannot be sufficiently cured, and problems such as being unable to adhere to the mold after crosslinking occur.

When heat-polymerizing the said resin composition, a thermal polymerization initiator can be contained in a resin composition as needed. Examples of the thermal polymerization initiator used in this case include benzoyl peroxide, diisopropyl peroxycarbonate, t-butylperoxy (2-ethylhexanoate) and the like as radical generators, and aromatic as a cation generator. Examples include sulfonium salts, aromatic iodonium salts, ammonium salts, aluminum chelates, and boron trifluoride amine complexes. The amount used is preferably 3 parts by weight or less with respect to 100 parts by weight of the organic component containing the functional group in the resin composition.

In the transparent film of the present invention, as described above, the spherical particles are dispersed with the average particle diameter as described above. As the spherical particles for such a dispersed state, the standard deviation of the particle diameter is used. Is preferably within 10%.

Examples of such spherical particles include silicon-containing metal oxide (fine) particles, semiconductor (fine) particles, and the like.
As the metal oxide fine particles containing silicon, dried powdery silica fine particles and colloidal silica (silica sol) dispersed in an organic solvent can be used. From the viewpoint of dispersibility, it is preferable to use colloidal silica (silica sol) dispersed in an organic solvent.

As the organic solvent in the case of using colloidal silica (silica sol) dispersed in the organic solvent, it is preferable to use an organic solvent in which the organic component used in the resin composition is dissolved. For example, alcohols, ketones, esters And glycol ethers. Colloidal silica, silica sol, silica fine particles dispersed in alcoholic solvents such as methanol, ethanol, isopropyl alcohol, butyl alcohol and n-propyl alcohol, and ketone organic solvents such as methyl ethyl ketone and methyl isobutyl ketone for ease of solvent removal Is preferable, and colloidal silica dispersed in isopropyl alcohol is more preferable. In particular, when colloidal silica dispersed in isopropyl alcohol is used, it is suitable for stably producing a composite composition having a low viscosity after solvent removal compared to other solvent systems and a low viscosity.

Colloidal silica (silica sol) and silica fine particles dispersed in these organic solvents are surface-treated with coupling agents such as silane coupling agents and titanate coupling agents as long as the required properties are not significantly impaired. In order to disperse in an organic solvent, a dispersant such as a surfactant may be used.

The semiconductor fine particle is not particularly limited as long as it has a property of emitting light having a wavelength inversely proportional to the difference between the two energy orders by absorbing energy such as light or an electron beam. The contained fine particles are preferably used.
As a chalcogenide, a compound containing chalcogen (a general term for five elements of the group VI elements of the periodic table: oxygen (O), sulfur (S), selenium (Se), tellurium (Te), polonium (Po)) In particular, II-VI group compounds which are compounds of Group II elements and Group VI elements of the Periodic Table are preferred. More preferably, it is at least one selected from ZnS, CdS, ZnSe, CdSe, ZnTe, CdTe, and ZnO.

In order to increase the issuance efficiency, the semiconductor fine particles are preferably formed by uniformly dispersing semiconductor ultrafine particles having a particle diameter smaller than twice the Bohr radius in the matrix without aggregation. Various inorganic substances and organic substances can be used for the matrix. Examples of inorganic substances include silicon compounds. Examples of the organic material include polyimide and a resin having an alicyclic structure from the viewpoint of heat resistance. A coupling agent containing silicon or titanium in the matrix can also be used.

Although content of the said spherical particle is not specifically limited, 5-80 volume% of the whole said transparent film is preferable, and 20-40 volume% is especially preferable. If the content is within the above range, the composition before the production of the transparent film has good fluidity and dispersibility, so that the film can be easily produced and exhibits a structural color while maintaining the transparency. Can be made easy to manufacture.

The average particle size of primary particles of such spherical particles is not particularly limited, but is preferably 15 to 400 nm, more preferably 20 to 150 nm, and most preferably 40 to 60 nm in terms of the balance between transparency and fluidity. It is. If the average particle size is less than the lower limit, the viscosity of the prepared composition is extremely increased, so that the filling amount of the spherical particles is limited and the dispersibility is lowered, and sufficient transparency may not be obtained. It was. Further, if the upper limit is exceeded, the transparency may be significantly reduced.

The refractive index difference between the transparent resin and the spherical particles is not particularly limited, but is preferably 0.1 or less, particularly preferably 0.05 or less. When the refractive index difference is within the above range, the transparency is particularly excellent.

The average inter-particle distance of the spherical particles dispersed in the transparent film is not particularly limited, but in the case of a film particularly excellent in transparency and blue color developability, it is preferably 100 to 350 nm, particularly 120 to It is preferable that it is 180 nm. In the case of a film excellent in transparency and green color developability, it is preferably 180 to 350 nm, and particularly preferably 210 to 270 nm. Moreover, in the case of a film excellent in transparency and red color developability, the thickness is preferably 250 to 400 nm, particularly preferably 300 to 360 nm.
The average interparticle distance can be evaluated by, for example, a scanning electron micrograph.

Further, in order not to reduce the light transmittance at a wavelength of 300 to 700 nm, it is preferable to use spherical particles in which fine particles having a primary particle size of 400 nm or more are present at a ratio of 5% or less, and the ratio is 0. % Is more preferable.

In such a transparent film, in order to exhibit structural color development while maintaining transparency, it is preferable that the arrangement of the spherical particles in the transparent film has a packed arrangement structure.
Here, the packed arrangement structure means that the particles are packed in a form so as to be finally packed into the hexagonal close-packed structure.
Here, for the presence or absence of the packed arrangement structure, for example, in the small-angle X-ray scattering profile obtained by small-angle X-ray scattering measurement of the transparent composite film, there are at least 5 peaks corresponding to the particle diameter, preferably higher order When peak tops are observed at regular intervals up to the peak, it is determined that the primary particles of the fine particles have a packed arrangement structure.

If necessary, the resin composition described above can be used in combination with a thermoplastic or thermosetting oligomer or polymer as long as the properties such as transparency, solvent resistance, and heat resistance are not impaired. If necessary, a small amount of a filler such as an antioxidant, an ultraviolet absorber, a dye, and other inorganic fillers, as long as the properties such as transparency, solvent resistance, liquid crystal resistance, and heat resistance are not impaired. Etc. may be included.

In the transparent film of the present invention, transparency means the amount of light transmitted through the film, and the composite film having high transparency means that the amount of transmitted light is large. The transparency is determined by measuring the total light transmittance of a transparent composite film (thickness: 200 μm) with a D65 standard light source, and determining that the transparency is 70% or more.

The method for producing the transparent composite film as described above will be described by taking as an example the case of using a resin composition containing a transparent resin and a curing agent and using silica (silica sol) as spherical particles.
(1) A method of removing an organic solvent by mixing colloidal silica (silica sol) dispersed in an organic solvent with a resin composition and other blends and, if necessary, reducing the pressure while stirring.
(2) A method in which colloidal silica (silica sol) dispersed in an organic solvent is mixed with a resin composition and other blends, and if necessary, after removing the solvent, casting and further removing the solvent,
(3) A method in which powdery silica fine particles, a resin composition and other blends are mixed and dried using a mixing apparatus having a high dispersion ability, and the like.

Among these methods, a method of dispersing spherical particles is important. Examples of a device having a high dispersion capacity include a film mix manufactured by Tokushu Kika Kogyo Co., Ltd. and various bead mills. When using a device with high dispersion capacity, care must be taken not to raise the temperature too much during mixing or kneading so that the reaction does not proceed rapidly.

The temperature for removing the organic solvent in producing the transparent composite film is preferably maintained at 30 to 100 ° C., more preferably 30 to 70 ° C. in balance with the solvent removal speed, and most preferably 35 ~ 60 ° C. If the temperature is raised too much, the fluidity may be extremely lowered or gelled, making it difficult to form a film.

When using colloidal silica dispersed in an organic solvent, the organic solvent may remain in the resin composition. When an organic solvent is contained, a post-treatment step such as heat treatment may be provided, and finally the organic solvent may be desorbed from the resin composition. The content of the organic solvent in the resin composition is a resin composition in order to avoid problems such as foaming, waviness in the film, and coloring in the step of removing volatile components by a crosslinking step or heat treatment. The total amount is preferably 10% by weight or less, more preferably 5% by weight or less, and most preferably 3% by weight or less.

Then, the resin composition described is cured and crosslinked with heat, light, etc. to obtain a transparent composite film.
As a method for forming a film, a method is used in which a composite composition is cast and dried as necessary. A spacer is provided so that a desired film thickness can be obtained between a glass plate, a plastic plate, a metal plate, etc. having surface smoothness. There is a method of sandwiching the resin composition. When the latter is used for curing with active energy rays or the like, at least one of them needs to use a transparent glass plate or plastic plate.

As a method of crosslinking the resin composition, there are a method of curing with active energy rays, a method of thermal polymerization by applying heat, and the like, and these can be used in combination. The active energy ray used is preferably ultraviolet rays. Examples of the lamp that generates ultraviolet rays include a metal halide type and a high-pressure mercury lamp.

When heat treatment is performed at a high temperature after curing by active energy rays and / or crosslinking by thermal polymerization, 200 ° C. to 300 ° C. in a nitrogen atmosphere or in a vacuum state for the purpose of reducing the linear expansion coefficient during the heat treatment step. It is preferable to include a heat treatment step at 1 ° C. for 1 to 24 hours.

In the resin composition, a polymerization inhibitor may be contained for the purpose of preventing the polymerization reaction from proceeding at the time of preparing the resin composition and increasing the viscosity. For the purpose of completing the curing reaction and removing volatile matter, it is preferable to use a heat treatment step at a higher temperature in combination.

(Reflective color film substrate)
The reflective color film substrate of the present invention is composed of the above-described transparent composite film. Such a transparent composite film develops color without using a coloring material, and thus has excellent transparency, heat resistance, and durability. Specifically, a transparent plate, an optical lens, an optical disk substrate, and a plastic for a liquid crystal display element are used as electronic substrates. It can be used for substrates, color filter substrates, plastic substrates for organic EL display elements, solar cell substrates, touch panels, optical elements, optical waveguides, and the like.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example and a comparative example, this invention is not limited to this.

Example 1
1. Manufacture of composite composition Norbornane dimethylol diacrylate (TO-2111; manufactured by Toagosei Co., Ltd.) 5 having a structure in which X, R ³ and R ⁴ are all hydrogen and p is 0 in the chemical formula (2). Part by weight, 1 part by weight of γ-acryloxypropylmethyldimethoxysilane, 20 parts by weight of isopropyl alcohol-dispersed colloidal silica (silica content 15% by weight, average particle size 120 nm, manufactured by Nissan Chemical Co., Ltd.) Volatiles were removed under reduced pressure. Then, 0.03 parts by weight of 1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184 manufactured by Ciba Specialty Chemicals) as a photopolymerization initiator was added and dissolved, and then the volatile components were removed under reduced pressure to obtain a composite. A composition was obtained.
The solvent content in the composite composition was less than 10%. The average particle diameter of the spherical particles in the composite composition was 120 nm, and the average interparticle distance of the spherical particles was 152 nm.
The silica volume fraction was 33 vol% from the weight residue after heating at 400 ° C. for 1 hour after curing annealing of the composite composition. The refractive index difference between the transparent resin used and the spherical particles was 0.1 or less.

2. Film formation The obtained composite composition is heated in an oven at a predetermined temperature (60 to 80 ° C.), poured into a 0.4 mm thick frame formed on the glass plate, and placed on the glass plate from above. Was filled with the composite composition. The composite composition sandwiched between the glass plates was cured by irradiating with UV light of about 500 mJ / cm ² from both sides, and the film was peeled from the glass.
Each film peeled from the glass was heated in a vacuum oven at about 100 ° C. for 3 hours, and further heated at about 275 ° C. for 3 hours to obtain an optical film.

(Example 2)
In Example 1, 20 parts by weight of isopropyl alcohol-dispersed colloidal silica was formed into a film with a silica content of 33 vol% and an average particle size of 250 nm (manufactured by Nissan Chemical Co., Ltd.). The silica volume fraction was 50% by weight. The refractive index difference between the transparent resin used and the spherical particles was 0.1 or less.

(Example 3)
Similarly, in Example 1, 20 parts by weight of isopropyl alcohol-dispersed colloidal silica was made into a film with a silica content of 50 vol% and an average particle diameter of 250 nm (Nissan Chemical). The silica volume fraction was 80% by weight. The refractive index difference between the transparent resin used and the spherical particles was 0.1 or less.

Example 4
The films prepared in Examples 1 to 3 were stacked and thermocompression bonded into a single film.

(Comparative Example 1)
In the chemical formula (2), 5 parts by weight of norbornane dimethylol diacrylate (TO-2111; manufactured by Toagosei Co., Ltd.) having a structure in which X, R ³ and R ⁴ are all hydrogen and p is 0, γ-acryl Contains 1 part by weight of roxypropylmethyldimethoxysilane and 20 parts by weight of isopropyl alcohol-dispersed colloidal silica (silica content 30% by weight, average particle size 10 nm, manufactured by Nissan Chemical Co., Ltd.) and removes volatiles under reduced pressure while stirring at 40 ° C. did. Then, 0.03 parts by weight of 1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184 manufactured by Ciba Specialty Chemicals) as a photopolymerization initiator was added and dissolved, and then the volatile components were removed under reduced pressure to obtain a composite. The procedure was the same as Example 1 except that the composition was obtained. The solvent content in the composite composition was less than 10%. The average particle diameter of the spherical particles in the composite composition was 10 nm, and the average interparticle distance of the spherical particles was 336 nm. The silica volume fraction was 33 vol% from the weight residue after heating at 400 ° C. for 1 hour after curing annealing of the composite composition. The refractive index difference between the transparent resin used and the spherical particles was 0.1 or less.

(Comparative Example 2)
In chemical formula (2), 5 parts by weight of norbornane dimethylol diacrylate (TO-2111; manufactured by Toagosei Co., Ltd.) having a structure in which X, R ³ and R ⁴ are all hydrogen and p is 0, γ-acryloxy 1 part by weight of propylmethyldimethoxysilane and 20 parts by weight of isopropyl alcohol-dispersed colloidal silica (silica content 30% by weight, average particle size 300 nm, manufactured by Nippon Shokubai Co., Ltd.) were added, and volatile components were removed under reduced pressure while stirring at 40 ° C. . Then, 0.03 parts by weight of 1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184 manufactured by Ciba Specialty Chemicals) as a photopolymerization initiator was added and dissolved, and then the volatile components were removed under reduced pressure to obtain a composite. The procedure was the same as Example 1 except that the composition was obtained. The solvent content in the composite composition was less than 10%. The average particle diameter of the spherical particles in the composite composition was 300 nm, and the average interparticle distance of the spherical particles was 650 nm. The silica volume fraction was 33 vol% from the weight residue after heating at 400 ° C. for 1 hour after curing annealing of the composite composition. The refractive index difference between the transparent resin used and the spherical particles was 0.1 or less.

The following evaluation was performed about the composite composition obtained by each Example and the comparative example. The evaluation items are shown together with the contents. The obtained results are shown in Table 1.
1. Presence or absence of structural coloration The presence or absence of structural coloration was evaluated by the wavelength dependence of the total light transmittance. The wavelength dependence of the total light transmittance was measured with a spectrophotometer U3200 (manufactured by Hitachi, Ltd.). The light transmittance in the blue wavelength region (300 to 500 nm) where the structural color development occurs in the light transmittance of the wavelength dispersion of the transparent film has a reflectance of 30% or more, the light transmittance in the green wavelength region (500 to 600 nm) In which the reflectance was 30% or more, and the light transmittance in the red wavelength region (600 to 750 nm) was 30% or more.

2. Transparency (haze and total light transmittance)
Transparency (haze and total light transmittance) was measured using NDH2000 manufactured by Nippon Denshoku Industries Co., Ltd.

3. Average particle diameter of spherical particles The average particle diameter of spherical particles was measured with a small-angle scatterometer equipped with an imaging plate detector adjusted to a wavelength of 1.5 mm and a camera length of 6 m using SPring8 high-intensity synchrotron radiation, BL08B2 line. did. The average particle diameter of the spherical particles was calculated from the plot of q and I (q) shown in FIG. 1 using NANO-Solver software manufactured by Rigaku Corporation.

As is apparent from Table 1, Examples 1 to 3 have a reflectance of 3 for each light transmittance.
% Or more and light emission (structural color development) was confirmed.

Claims (8)

A transparent film containing a transparent resin and spherical particles,
A transparent film, wherein the spherical particles have an average particle diameter of 40 to 200 nm and are dispersed in the transparent film. The relationship between the average particle diameter of the spherical particles dispersed in the transparent film, and the interparticle distance,
(1) Transparent film having an average particle diameter of 40 to 60 nm and an interparticle distance of 120 to 180 nm (2) Transparent film having an average particle diameter of 70 to 90 nm and an interparticle distance of 210 to 270 nm (3) Average particle diameter of 100 to 2. The transparent film according to claim 1, wherein the transparent film is a laminated film in which at least two of three transparent films of a transparent film having a thickness of 120 nm and an interparticle distance of 300 to 360 nm are laminated. The transparent film according to claim 1 or 2, wherein the content of the spherical particles is 5 to 80% by volume of the entire transparent film.   The transparent film according to any one of claims 1 to 3, wherein an average inter-particle distance of the spherical particles dispersed in the transparent film is 120 to 360 nm. The transparent film according to claim 1, wherein the transparent resin is one of an epoxy resin and an acrylic resin. The transparent film according to claim 1, wherein the spherical particles are metal oxide particles containing silicon. The transparent film according to claim 1, wherein a difference in refractive index between the transparent resin and the spherical particles is 0.1 or less.   A reflective color film substrate comprising the transparent film according to any one of claims 1 to 7.

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