TW202142628A - Spherical alumina particle dispersion for optical film with improved viewing angle, coating layer forming resin composition for optical film with improved viewing angle, and optical film with improved viewing angle, and manufacturing method of spherical alumina particle dispersion - Google Patents

Abstract

The subject of the invention is to provide a method for improving viewing angle characteristics of a light scattering layer provided on a surface of a liquid crystal panel. The solution is a method for manufacturing a dispersion of spherical alumina particles, which contain spherical alumina particles, a dispersant, and a solvent. The method includes the step of dispersing the spherical alumina particles, which involves dispersing a liquid having raw material alumina particles, a dispersant and a solvent with beads having an average particle size of less than 0.10 mm, so that the raw material alumina particles are dispersed into spherical alumina particles with an average particle size of 1 to 10 [mu]m. The alumina particles are used as the raw material for the spherical alumina particles. The dispersant includes at least one selected from a nonionic dispersant and a cationic dispersant.

Description

Manufacturing method of spherical alumina particle dispersion, spherical alumina particle dispersion for improving viewing angle optical film, coating film forming resin composition for improving viewing angle optical film, and viewing angle improvement optical film

The present invention relates to a method for producing a dispersion of spherical alumina particles, a dispersion of spherical alumina particles for an optical film for improving viewing angle, a resin composition for forming a coating film for optical film for improving viewing angle, and an optical film for improving viewing angle .

In recent years, liquid crystal display devices have been widely used as display devices for televisions and mobile terminals. However, when viewed from an oblique plane, the liquid crystal display device is known to cause hue reversal, color shift, and decrease in contrast. As a countermeasure for this improvement, (1) a method of disposing a retardation film between a liquid crystal panel and a polarizing plate of a liquid crystal display device, and (2) a method of disposing a light scattering layer on the surface of the liquid crystal panel (for example, Patent Document 1). Among them, the method (2) is considered to be superior in the effect of improving the viewing angle characteristics compared with the method (1). However, even with the method of (2), the current situation is still unable to achieve a sufficient improvement in viewing angle characteristics. [Prior Technical Literature] [Patent Literature]

[Patent Document 1] International Publication No. 2010/143552

[The problem to be solved by the invention]

Therefore, the object of the present invention is to provide a technology that can improve the viewing angle characteristics of the light scattering layer provided on the surface of the liquid crystal panel. [Means to solve the problem]

The inventors of the present invention conducted a review on improving the viewing angle characteristics of the light scattering layer disposed on the surface of the liquid crystal panel as in the aforementioned method (2). The light-scattering layer is generally composed of a film formed by dispersing a light-scattering agent that scatters the light in a polymer that allows light from the backlight to pass through. Therefore, in order to improve the viewing angle characteristics, that is, to expand the viewing angle, the penetration of the light from the backlight is ensured, and at the same time, the light scattering agent is used to make the light scatter better than before. The concept of perspective enhancement. In addition, after careful review, in order to achieve this issue, the idea of reducing the particle size of the light scattering agent to make it uniformly dispersed into an effective one was developed. Many amorphous particles generate Rayleigh scattering in the light scattering layer, which causes the light of a specific wavelength (especially, the wavelength of 900nm) to be emphasized.

After further review, it was found that when the specific particles that become the light scattering agent are dispersed, by using beads of a specified size for dispersion treatment, the formation of amorphous particles can be suppressed, and the particles are substantially spherical. As a result, it can suppress the Rayleigh scattering in the light scattering layer. In addition, it was found that by using a specific dispersant, the aggregation of the light scattering agent, that is, the specific fine particles, can be suppressed. As a result, the light scattering layer can ensure the uniform dispersion of the light scattering agent. That is, it was discovered that by making the light scattering agent, that is, the fine particles substantially spherical, and ensuring the dispersibility of the spherical fine particles in the light scattering layer, the Rayleigh scattering can be suppressed and the light scattering effect can be improved more than before. Improved, and can form a light scattering layer with improved viewing angle characteristics.

The first aspect of the present invention relates to a method for manufacturing a dispersion of spherical alumina particles, which is a method for manufacturing a dispersion of spherical alumina particles comprising spherical alumina particles, a dispersant, and a solvent, and includes: The liquid containing raw alumina particles, dispersant and solvent is dispersed together with beads with an average particle diameter of less than 0.10 mm, so that the aforementioned spherical alumina particles are substantially spherical with an average particle diameter of 1-10 μm The step of dispersing raw alumina particles in a manner that is composed of alumina particles; the raw alumina particles become the raw material of the aforementioned spherical alumina particles, and the dispersant includes a nonionic dispersant and a cationic dispersant At least one of them.

In the embodiment of the present invention, the aforementioned dispersant may include a nonionic dispersant and a cationic dispersant. In addition, the cationic dispersant may be an amine polymer dispersant.

In the embodiment of the present invention, the average particle size of the aforementioned raw alumina particles may be 1-10 μm.

The second aspect of the present invention relates to a method for manufacturing a coating film forming composition, which includes: a step of preparing a dispersion of spherical alumina particles, which is to prepare a liquid containing raw alumina particles, a dispersant, and a solvent, and Beads with an average particle size of less than 0.10 mm are dispersed together to disperse the raw alumina particles in such a way that the aforementioned spherical alumina particles are substantially composed of spherical alumina particles with an average particle size of 1 to 10 μm. The raw alumina particles are those that become the raw materials for the spherical alumina particles, and the dispersant contains at least one selected from the group consisting of nonionic dispersants and cationic dispersants; and, the coating film forming composition preparation step, which is The coating film forming component is added to the spherical alumina particle dispersion obtained in the step of preparing the spherical alumina particle dispersion and subjected to agitation treatment.

The third aspect of the present invention relates to a method for producing a cured film, which includes a step of preparing a dispersion of spherical alumina particles. Beads of less than 0.10 mm are dispersed together to disperse the raw alumina particles so that the aforementioned spherical alumina particles are substantially composed of spherical alumina particles with an average particle diameter of 1-10 μm. Alumina particles are used as the raw material for the spherical alumina particles. The dispersant contains at least one selected from a nonionic dispersant and a cationic dispersant; the coating film forming composition preparation step is to oxidize the spherical alumina particles. The spherical alumina particle dispersion obtained in the aluminum particle dispersion preparation step is mixed with the coating film forming components; and, the cured film formation step is to apply the coating film forming composition obtained in the coating film forming composition preparation step A coating film is formed on the surface of the base material and cured to form a cured film.

In the embodiment of the present invention, the above-mentioned cured film may be an optical film for improving the viewing angle.

The fourth aspect of the present invention relates to a dispersion of spherical alumina particles for improving viewing angle optical films, which contains spherical alumina particles, a dispersant, and a solvent. Comprised of spherical alumina particles with a diameter of 1-10 μm, the dispersant includes at least one selected from a nonionic dispersant and a cationic dispersant. In the embodiment of the present invention, the aforementioned dispersant may include a nonionic dispersant and a cationic dispersant.

The fifth aspect of the present invention relates to a coating film-forming composition for a viewing angle-improving optical film, which contains the spherical alumina particle dispersion and a coating film-forming component for the viewing angle-improving optical film as described above. In the embodiment of the present invention, alcohols may also be included.

The sixth aspect of the present invention relates to a viewing angle improvement optical film, which is a cured film of the aforementioned coating film forming composition for viewing angle improvement optical film.

The ratio of the transmittance of white light at a wavelength of 900nm to a wavelength of 350nm (900nm/350nm) of the viewing angle-improving optical film of the embodiment of the present invention is less than 3.10, The penetrating light intensity of the white light at an incident angle of 0° relative to the surface of the cured film is 2900 or more, and the penetrating light intensity of the white light at the aforementioned incident angle of 5° is 430 or more. [Effects of the invention]

According to the present invention, it is possible to provide a technology for improving the viewing angle characteristics of the light scattering layer disposed on the surface of the liquid crystal panel.

The method for producing a dispersion of spherical alumina particles according to an embodiment of the present invention is a method of producing a dispersion of spherical alumina particles including spherical alumina particles, a dispersant, and a solvent. The manufacturing method includes: mixing the raw alumina particles that are the raw materials for the spherical alumina particles, a liquid containing at least one dispersant selected from the group consisting of a nonionic dispersant and a cationic dispersant, and a solvent (hereinafter referred to as "Raw material solution"), together with beads with an average particle size of less than 0.10mm, are dispersed together so that the aforementioned spherical alumina particles are substantially composed of spherical alumina particles with an average particle size of 1-10μm The way to disperse the raw alumina particles.

The raw material alumina particles are not particularly limited, and conventionally known alumina particles can be used, and commercially available ones can be used. The alumina particles only need to have alumina as the main component, and may also contain other components. In addition, it may be a person who has been surface-treated. The shape of the raw material alumina is not particularly limited. From the viewpoint of the production efficiency of spherical alumina particles, spherical alumina particles are preferred. The average particle size of the spherical alumina particles as the raw material alumina particles is preferably 1-10 μm.

The content of the raw alumina particles in the total raw material liquid is preferably 25.0-70.0% by weight, preferably 25.0-65.0.

The dispersing agent may contain at least one type of dispersing agent selected from the group consisting of nonionic dispersing agents and cationic dispersing agents. Those with active ingredients, those containing non-ionic dispersants and cationic dispersants as active ingredients. Among them, those containing a nonionic dispersant and a cationic dispersant as effective ingredients, that is, a nonionic dispersant and a cationic dispersant are preferably used. In particular, when these two dispersants are used, there is a tendency that the obtained spherical alumina particles can be more uniformly dispersed in the dispersion and the coating film forming composition. The reason is not sufficiently clear, but it is considered that (a) the adsorption force of nonionic dispersant on alumina particles is weak, (b) the adsorption force of cationic dispersant on alumina particles is excessively strong, (c ) In the case of using the two together, the nonionic dispersant has been mixed between the cationic dispersants adsorbed on the alumina particles, and it is presumed that the agglomeration of the alumina particles is more effectively suppressed.

It does not specifically limit as a nonionic dispersing agent, A well-known thing can be used. For example, a polymer compound having a polyoxyethylene chain, etc. can be mentioned. As the polymer compound having a polyoxyethylene chain, for example, alkyl polyoxyethylene ether, alkyl polyoxyethylene·polyoxypropylene ether, alkyl polyoxypropylene·polyoxyethylene ether, polyoxyethylene·poly Oxypropylene ether (polyoxyethylene oxypropylene block copolymer), fatty acid polyoxyethylene ester, fatty acid polyoxyethylene sorbitan ester, fatty acid polyoxyethylene sorbitan ester, polyoxyethylene sorbitan monoalkyl ether, poly Oxyethylene alkyl ether sulfate, polyoxyethylene castor oil (hardened castor oil), acetylene glycol ethylene oxide adduct, etc. Examples of alkyl polyoxyethylene ethers include polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene octyl ether, and polyoxyethylene hexadecyl ether. Ether, polyoxyethylene octyl phenyl ether, polyoxyethylene nonyl phenyl ether, etc. As fatty acid polyoxyethylene rowan monolaurate, for example, polyoxyethylene rowan monolaurate etc. are mentioned.

It does not specifically limit as a cationic dispersing agent, A well-known thing can be used. For example, alkyl amine salt, amide amine salt, quaternary ammonium salt, ammonium salt having amide bond, ester bond or ether bond, imidazoline, imidazolium salt, amine derivative, etc. The cationic dispersant may be a low-molecular compound or a high-molecular compound. From the viewpoint of the dispersibility of alumina particles, a high-molecular compound is preferred. Examples of such polymer-based dispersants include polyethyleneimine, aminoalkyl (meth)acrylate copolymers, polyvinyl imidazoline, polyvinyl pyridine derivatives, polyoxyethylene alkyl Amine, polyoxyethylene alkyl amide, etc. Examples of polyvinylpyridine derivatives include copolymers of vinyl pyridine and (meth)acrylic acid, copolymers of vinyl pyridine, (meth)acrylic acid and oxyethylene polymer compounds, etc. . The copolymer of vinyl pyridine, (meth)acrylic acid and a polymer compound containing oxyethylene group, for example, a copolymer of vinyl pyridine and (meth)acrylic acid and a copolymer of polyoxyethylene. Among them, from the viewpoint of the dispersibility of alumina particles, an amine-type polymer dispersant is preferred.

The combination of non-ionic dispersant and cationic dispersant can be selected in consideration of the relationship with other components, etc. It is better that both are polymer-based dispersants, and the block of the polymer compound constituting the two includes A common constituent unit is preferred. For example, it is more preferable that the two dispersants have polyoxyethylene chains.

The content of the nonionic dispersant and the cationic dispersant is not particularly limited, and can be selected in consideration of the relationship with other components. The non-ionic dispersant is preferably 0.75 to 6.0% by weight (based on solid content (non-volatile content)) in the total amount of the raw material liquid. The cationic dispersant is preferably 0.7 to 5.0% by weight (based on solid content (non-volatile content)) in the total amount of the raw material liquid. The mixing ratio of the two is also not particularly limited, and it can be selected in consideration of the characteristics of the two dispersants and the relationship with other components. From the viewpoint of the dispersibility of alumina particles, the mixing ratio of the two components is preferably the one containing more non-ionic type.

The solvent system can be appropriately selected according to the types of coating film forming components described later, and examples thereof include various organic hydrocarbons such as aromatic hydrocarbons, aliphatic hydrocarbons, ketones, esters, glycol ethers, and alcohols. Solvent, water, etc. Among them, from the viewpoint of environmental friendliness, water is particularly preferred.

The content (addition amount) of the solvent is preferably 20-40% by weight in the total amount of the raw material liquid.

The raw material liquid may contain other ingredients as necessary. Examples of such additives include defoamers and the like.

The defoamer is foaming during the dispersing process, and it can be used for the purpose of suppressing and breaking foam. Examples of such antifoaming agents include silicone-based, surfactant-based, mineral oil-based, and the like. The form of the silicone-based defoaming agent is also not particularly limited. For example, (a) O/W emulsion type in which silicone oil and silica particles are emulsified with, for example, a nonionic surfactant, (b) Oil type composed of silicone oil, (c) Solution type formed by dissolving silicone oil in a hydrocarbon solvent, (d) Foam breaking polysiloxane, hydrophobic particles and polyglycerol (polyglycerol) ) Mixtures and so on. The content of the defoamer is not particularly limited. For example, it can be 0.001 to 0.1 parts by weight (based on solid content (non-volatile content)) relative to 100 parts by weight of spherical alumina particles.

The average particle size of the beads used in the dispersion treatment is less than 0.10 mm. From the viewpoint of maintaining the shape of the alumina particles in a spherical shape while simultaneously dispersing, that is, preventing Rayleigh scattering, it is preferably 0.08 mm or less, preferably 0.06 mm or less, and more preferably 0.05 mm or less. From the viewpoint of not crushing the alumina particles and not generating Rayleigh scattering, it is preferably 0.05 mm or less.

The material of the beads is not particularly limited, and known ones can be used. For example, zirconia, alumina, zircon, glass, etc. can be mentioned. In the case that the input amount of beads is batch type, relative to the volume of the mill base in the grinder, the beads should be adjusted to 40~80% by volume, preferably 50~70% by volume. In the case of the circulation type, relative to the capacity of the grinder, it is better to adjust it to 40-80% by volume, preferably 50-70% by volume.

The manufacturing method of the spherical alumina particle dispersion of the embodiment is to mix the aforementioned components to prepare a raw material liquid, to make the beads exist in the raw material liquid, and to perform a dispersion treatment. The dispersion treatment system can be performed by a bead mill, a mass colloid mill (masscolloder), a ball mill, a sand mill, or the like. The conditions of the dispersion treatment are not particularly limited. For example, in the case of a sand mill, it is appropriate to perform 1 to 2 hours at 25 to 40°C at 1500 rpm to 2000 rpm.

After the dispersion treatment, remove the beads as necessary. Beads can be removed by filtration or the like. Moreover, if necessary, the aforementioned solvent may be added before or after the beads are removed. The solvent to be added is not particularly limited, and it is preferable to use the same solvent as that used in the dispersion treatment. Moreover, the addition amount at the time of adding a solvent can be suitably determined, for example, it can add so that the content of a solid content may become 30-60 weight%. With this operation, a dispersion of spherical alumina particles can be obtained.

In the spherical alumina particle dispersion obtained by the above operation, the alumina particles are destroyed and the generation of amorphous alumina particles is suppressed, and there are spheres composed of substantially spherical particles. Alumina particles, so the Rayleigh scattering caused by the amorphous alumina particles in the coating film described later will be suppressed. In addition, by using the aforementioned dispersing agent, especially the specified two kinds of dispersing agents, since the spherical alumina particles composed of spherical particles with an average particle diameter in the specified range can be uniformly dispersed in the coating film, Therefore, the light scattering effect of the spherical alumina particles is good, and the effect of energy and viewing angle is enlarged. Therefore, such a spherical alumina particle dispersion system is suitable as, for example, an optical film for improving the viewing angle. In addition, this spherical alumina particle dispersion system is described later. When using this to form a cured film, Rayleigh scattering is suppressed. For example, the ratio of the transmittance of white light at a wavelength of 900nm to a wavelength of 350nm (900nm/350nm) ) Will become less than 3.10.

From the viewpoint of improving the viewing angle, the average particle size of the spherical alumina particles is 1-10μm. 1~4μm is better. The average particle size can be measured by, for example, a laser diffraction/scattering particle size distribution measuring device (manufactured by Horiba Manufacturing Co., Ltd., LA-950 type, etc.). As mentioned above, the spherical alumina particles contained in the dispersion are substantially composed of spherical alumina particles with an average particle diameter within a specified range. Here, "spherical alumina particles" does not mean particles limited to real spheres, but means the result of dispersion treatment using beads, and does not include alumina in amorphous shapes such as defective shapes. particle. "Substantially" does not mean that alumina particles of such an amorphous shape are not included at all, but means that they are allowed to be included to the extent that they can prevent Rayleigh scattering as described later.

Next, the method of manufacturing the coating film forming composition of the embodiment of the present invention will be explained. This embodiment uses the spherical alumina particle dispersion obtained by the aforementioned operation to produce a coating film forming composition. That is, the above-mentioned method of producing the spherical alumina particle dispersion corresponds to the step of preparing the spherical alumina particle dispersion in the method of producing the coating film forming composition. In addition, a coating film forming composition preparation step in which coating film forming components are added to the spherical alumina particle dispersion obtained in this step and agitated processing is performed.

As the coating film forming component, for example, a resin capable of forming a transparent cured film and the like can be mentioned. Examples of such resins include cellulose acetate resins such as triacetyl cellulose, (meth)acrylic resins such as polymethylmethacrylate and polyacrylate, and (meth)acrylic resins such as polymethylmethacrylate and polyacrylate. Acrylic alkyl-styrene copolymers, chlorinated vinyl resins, polycarbonate resins, polyester resins such as polyethylene terephthalate, polyolefins such as polyethylene, polypropylene, and polynorbornene Series resins, polystyrene resins, silicone resins, epoxy resins, melamine resins, etc. In addition, in order to increase the degree of hardening of the resin film for the purpose of abrasion resistance, heat resistance, and improvement of adhesion to the substrate, a hardener suitable for the aforementioned various resins may also be used.

Relative to 100 parts by weight of the spherical alumina particles in the dispersion of spherical alumina particles, the content of the coating film forming components is preferably 120 to 280 parts by weight (based on solid content (non-volatile content)).

The stirring treatment is not particularly limited, and can be performed by, for example, a disper, a shaker, or the like. The stirring temperature and time can be appropriately determined according to the composition of the ingredients.

During the stirring process, a solvent can be added as necessary. The solvent system can be used when preparing the spherical alumina particle dispersion. The solvent system to be added can be appropriately selected according to the solvent contained in the spherical alumina particle dispersion. For example, when the spherical alumina particle dispersion does not contain alcohols or ketones, the coating film or the cured film described later From the point of view that the smoothness is more improved, it is better to add a surface tension lower than that of the solvent used. The added solvents are preferably alcohols, ethers, and ketones. As alcohols, from the viewpoint of film forming properties, those with a boiling point of 25 to 83°C are preferred. Examples of such alcohols include monovalent alcohols with 1 to 3 carbon atoms, glycols, etc. However, there are solvents that dissolve the spherical alumina particle dispersion, or may interact with the spherical alumina It is necessary for the solvents contained in the particle dispersion to be compatible. Furthermore, for example, when preparing a spherical alumina particle dispersion using water as a solvent to prepare a coating film forming composition, it is preferable to add the aforementioned alcohol. The content of the added solvent is preferably 0.1 to 5.0% by weight in the coating film forming composition.

Since the coating film forming composition obtained by this operation contains the aforementioned alumina particle dispersion, the specified alumina particles and coating film forming components are uniformly dispersed, and the specified alumina particles can be uniformly dispersed. Coating. Therefore, the coating film forming composition has a good scattering effect of light formed by spherical alumina particles, and can expand the viewing angle of the cured film. In the case of alcohols, the viewing angle can be further expanded. Therefore, the coating film forming composition is suitable as, for example, an optical film for improving the viewing angle.

Next, a description will be given of the method of manufacturing the cured film of the embodiment of the present invention. In this embodiment, a cured film is produced using the coating film forming composition obtained by the foregoing operation. That is, the preparation step of the spherical alumina particle dispersion and the preparation step of the coating film forming composition in the method of manufacturing the cured film are the same as the method of manufacturing the coating film forming composition. In addition, the method for producing the cured film is to apply the coating film forming composition obtained in the aforementioned coating film forming composition preparation step to the surface of the substrate to form a coating film, and to harden it to form a cured film (cured film forming step ).

The usable substrate is not particularly limited as long as it is a transparent substrate. As the material constituting the substrate, for example, quartz glass, soda glass, polycarbonate, polymethyl methacrylate, polyvinyl chloride, polyester, cellulose acetate butyrate (Cellulose acetate butyrate), polyolefin, Polystyrene, epoxy resin, polyacrylate, silicone resin, transparent fluororesin, polyethylene terephthalate, cycloolefin polymer, polyimide, etc.

The shape of the substrate is not particularly limited, and, for example, a film shape can be mentioned. When the substrate is in the form of a film, its thickness can be made, for example, 10 to 3000 μm. In the case of constituting an optical film as an optical member, it can be made, for example, 10 to 300 μm.

As a method of applying the coating film forming composition to the surface of the substrate, a conventional method can be used. For example, a reverse roll coating method, a die coating method, a comma coater method, a die coater method, a spray coating method, a gravure coating method, and a rod coating method can be used. In addition to coating methods such as the rod coat method, brush coating, roller coating, spray coating, cationic electrodeposition coating, electrostatic coating, etc. can also be used.

The film thickness at the time of coating should preferably be 1~500μm in the dry state, preferably 1~200μm. In the case of optical film applications, it can be made, for example, from 1 to 100 μm.

The curing conditions can be appropriately determined in accordance with the coating film forming ingredients, etc.

Since the cured film obtained by the above operation is formed using the aforementioned coating film forming composition, it can form a coating film (before curing) in which the specified alumina particles are uniformly dispersed. Therefore, the cured film obtained is also the one where the specified alumina particles are uniformly dispersed. Therefore, the scattering effect of the light formed by the spherical alumina particles of the cured film is good, and the viewing angle is greatly improved. Therefore, the cured film is suitable as, for example, an optical film for improving the viewing angle. In addition, by containing alcohols in the coating film forming composition, the light scattering effect and viewing angle characteristics of the obtained cured film can be further improved, and the coating film forming composition is more suitable as an optical film for improving the viewing angle. The cured film It is more suitable as an optical film to improve the viewing angle. In addition, since the alumina particles have excellent heat dissipation characteristics, the heat dissipation effect by the uniformly dispersed designated alumina particles can also be expected. Therefore, the cured film is also suitable as a heat dissipation material. In addition, since the alumina particles have excellent heat dissipation characteristics, the heat dissipation effect by the uniformly dispersed designated alumina particles can also be expected. Therefore, the cured film is also suitable as a heat dissipation material.

In addition, when the cured film is suitable as an optical film for improving the viewing angle, from the viewpoint of suppressing Rayleigh scattering, the ratio of the transmittance of white light at a wavelength of 900nm to a wavelength of 350nm (900nm/350nm) is less than 3.10 Preferably, 3.00 or less is more preferable, 2.50 or less is more preferable, and 2.00 or less is particularly preferable. In addition, from the viewpoint of viewing angle, the transmitted light intensity of white light at 0° with respect to the surface of the cured film is 2900 or more, and the aforementioned white light at 5° The transmitted light intensity is preferably 430 or more, preferably 550 or more. The transmittance and intensity of the white light can be measured by, for example, the method described later. In addition, for example, compared with the cured film when the alcohol is not included, the penetration light intensity of the white light with the incident angle of 0° of the cured film obtained by using the coating film forming composition containing the alcohol is different from the incident light intensity. The ratio of the transmitted light intensity of the white light with an angle of 5° or -5° can be close to 1, that is, the viewing angle characteristics can be improved. [Example]

Hereinafter, the embodiments of the present invention will be described in detail based on examples.

(Example 1, Comparative Examples 1 to 4) <Production of alumina particle dispersion (preparation step of alumina particle dispersion)> Raw material alumina particles (made by Denka Co., Ltd., DAW-0105, spherical shape, average particle size: 2μm): 120.00 g (solid content), non-ionic dispersant (manufactured by BYK Chemie, DISPERBYK-193, with polymer High molecular compound of oxyethylene chain, solid content 40.3%): 23.16g, cationic dispersant (manufactured by BASF, Efka PX4701, propylene vinylene-vinylpyridine copolymer with polyoxyethylene chain, solid content 100%) : 5.07 g, silica-based defoamer (BYK Chemie, BYK-024, solid content 100%): 0.10 g, solvent (pure water): 51.67 g, mixed, and pre-dispersed to prepare a raw material liquid. Add 366.66g of zirconia beads with the average particle size shown in Table 1 to the raw material liquid (60% by volume relative to the volume of the grinding material of the grinder). Dispersion treatment was carried out at 25°C for 80 minutes. Thereafter, 40.00 g of pure water was added and filtered to remove the zirconia beads to obtain an alumina particle dispersion. In addition, in the "component composition of the cured film" in Table 1, the components other than the acrylic resin also have the same composition ratio in the solid content of the alumina particle dispersion.

<Production of coating film forming composition (coating film forming composition preparation step)> 30.00 g of the obtained alumina particle dispersion was mixed with 104.47 g of coating film forming ingredients (manufactured by Nissin Chemical Industry Co., Ltd., Vinyblan (registered trademark) 717L, acrylic resin, solid content 23.3%), and the solid content Pure water was added so that the concentration became 30% by weight, and stirred to obtain a coating film forming composition.

<Production of cured film (curing film formation step)> Using a bar coater, apply the obtained coating film forming composition to a polyethylene terephthalate film (manufactured by Toyobo Co., Ltd., Cosmoshine (registered trademark) A4100) so that the wet film thickness becomes 37.5 μm , It is dried at 60°C for 15 minutes to form a cured film. The obtained cured film was used for the evaluation described later.

(Evaluation) ＜Measurement of the average particle size of alumina particles＞ A laser diffraction/scattering particle size distribution measuring device (Horiba Manufacturing Co., Ltd., LA-950 type) was used to measure the average particle size of the alumina particles in the alumina particle dispersion.

＜Observation of the appearance of alumina particles＞ After adding 0.2 g of the obtained alumina particle dispersion and 1.0 g of distilled water to an aluminum container and stirring, it was heated at 130° C. for 16 hours and dried to obtain a sample for observation. Observe the acquired observation data with an electron microscope (manufactured by Thermoscinetific, Phenom ProX). The measurement condition is that the magnification is set to 5000 times, and the measurement mode is set to the acceleration voltage 15kV/mapping mode. The photography is shown in Figures 1~5.

＜Rayleigh scattering evaluation (white light transmittance)＞ Using the obtained cured film, measure the transmitted light spectrum with an ultraviolet-visible near-infrared spectrophotometer (manufactured by JASCO Corporation, V-670 UV/Vis/NIR Spectrophotometer), and calculate the wavelength at 900 nm and 350 nm The ratio of the transmittance of white light (900nm/350nm). Those whose ratio is less than 3.10 are evaluated as those whose Rayleigh scattering is suppressed. The evaluation results are shown in Table 1. Also, the spectrum of the transmitted light is shown in Figure 6.

(Examples 2, 3, Comparative Example 5) The zirconia beads used for the dispersion of the raw material liquid were the same as in Example 1, and except that the type and content of the dispersant used were shown in Table 2, the other systems were the same as in Example 1 to produce spherical alumina Particle dispersion, coating film forming composition, cured film. Use the obtained cured film to evaluate the viewing angle. In addition, it was confirmed that the average particle diameter and outer tube system of the alumina particles in the alumina particle dispersions obtained in Examples 2 and 3 were equivalent to those of Example 1. Furthermore, the aforementioned Rayleigh scattering evaluation results performed using the cured films obtained in Examples 2 and 3 confirmed that the specified ratio was less than 3.10. In the "component composition of the cured film" in Table 2, the components other than the acrylic resin also have the same composition ratio in the solid content of the alumina particle dispersion. In addition, as the anionic dispersant system, SN-Dispersant 5468 (solid content 41%) manufactured by SAN NOPCO Co., Ltd. was used.

＜Evaluation of viewing angle＞ Using GENESIA Gonio manufactured by GENESIA Co., Ltd., the transmitted light intensity of the white light obtained in Example 1 and Comparative Examples 5 to 7 with the incident angle to the surface of the cured film at 0° was measured, and the aforementioned incident angle was 5 The intensity of the penetrating light of the white light at °. The evaluation criterion is to evaluate the penetration light intensity of the white light at 0° relative to the surface of the cured film of 2900 or more, and the penetration light intensity of the white light at the aforementioned 5° angle of incidence is 430 or more Those who have achieved good viewing angles will be evaluated as those who have achieved better viewing angles above 550. Furthermore, the value of the incident angle of 5° is set as the smallest value among the transmitted light intensity at the incident angle of ±5°, which needs to be greater than the specified value.

The product composition and conditions of GENESIA Gonio Co., Ltd. are as follows. 1. Measuring machine GENESIA Gonio/Far Field Profiler 1-2. Light source White light source: made by Nichia Chemical Industry Co., Ltd., white LED (model NSPW300BS) 1-3. Detector Detector: manufactured by Hamamatsu Photonics Co., Ltd., Si photodiode (model S2386-5K) 1-4. Measurement conditions Through scattering measurement

As shown in Table 1, it is known that when the average particle diameter of the beads used in adjusting the alumina particle dispersion is less than 0.10mm, the ratio of the transmittance of white light at a wavelength of 900 nm to a wavelength of 350 nm (900nm /350nm) will be less than 3.10, and Rayleigh scattering is suppressed. This point can also be understood from Figure 6 (spectrum with wavelengths from 350 mm to 900 mm). As shown in Figure 6, it is known that in Comparative Examples 1 to 4, it is found that the Rayleigh scattering caused by the amorphous alumina particles (broken matter) increases the transmittance at long wavelengths and decreases the transmittance at short wavelengths. However, in Example 1, this was more suppressed than in the comparative example. In addition, as can be seen from the part surrounded by white lines in Comparative Example 1 of Fig. 2, there are obviously amorphous alumina particles in Comparative Examples 2 to 4 of Figs. 3 to 5. In contrast, the implementation of Fig. 1 In Example 1, almost no amorphous alumina particles were observed, and it was found that the spherical alumina particles were substantially composed of spherical alumina particles. And, as shown in Table 2, it is known that by using a dispersion of spherical alumina particles prepared by using designated beads and a specific dispersant, the incident angle of the cured film obtained is 0°, and even At ±5°, the transmitted light intensity of white light is above the specified value, and the viewing angle is improved.

(Example 4) <Production of spherical alumina particle dispersion (preparation step of spherical alumina particle dispersion)> In the same manner as in Example 1, a dispersion of spherical alumina particles was obtained.

<Production of coating film forming composition (coating film forming composition preparation step)> The obtained spherical alumina particle dispersion 30.00g, coating film forming ingredients (manufactured by Nissin Chemical Industry Co., Ltd., Vinyblan (registered trademark) 717L, acrylic resin, solid content 23.3%) 104.47g, alcohol (saga root) Produced by a product company, 1.39 g of isopropyl alcohol (IPA) was mixed, pure water was added so that the solid content concentration became 29.70% by weight, and the mixture was stirred to obtain a coating film forming composition.

<Production of cured film (curing film formation step)> The cured film was formed in the same manner as in Example 1. Using the cured film obtained, the aforementioned viewing angle evaluation was performed. The evaluation results are shown in Table 3.

(Example 5) In the manufacture of the coating film forming composition (coating film forming composition preparation step), except that methanol (MeOH) (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) was used as the alcohol instead of IPA, the other systems were the same as in Example 4 Operate to obtain a hardened film. The evaluation results are shown in Table 3.

(Example 6) In the manufacture of the coating film forming composition (coating film forming composition preparation step), the other systems were the same as in Example 4 except that ethanol (EtOH) (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) was used as the alcohol instead of IPA. Operate to obtain a hardened film. The evaluation results are shown in Table 3.

As shown in Table 3, it is known that by adding alcohols when preparing the coating film forming composition, each value becomes larger and the light scattering properties are improved, and 0° The ratio of +5° or -5° is close to 1, and the viewing angle characteristics are improved. In other words, it is known that the function of the cured film as a light-scattering film is improved by alcohols. It is speculated that the smoothness of the coating film is improved by alcohol, and as a result, the smoothness of the hardened film surface is improved.

[Fig. 1] A photograph showing an electron microscope photograph of alumina particles contained in the alumina particle dispersion obtained in Example 1. [Fig. [Fig. 2] A photograph showing an electron microscope photograph of alumina particles contained in the alumina particle dispersion obtained in Comparative Example 1. [Fig. [Fig. 3] A photograph showing an electron microscope photograph of alumina particles contained in the alumina particle dispersion obtained in Comparative Example 2. [Fig. [Fig. 4] A photograph showing an electron microscope photograph of alumina particles contained in the alumina particle dispersion obtained in Comparative Example 3. [Fig. [Fig. 5] An electron micrograph of the alumina particles contained in the alumina particle dispersion obtained in Comparative Example 4. [Fig. [Figure 6] A graph showing the transmitted light spectrum of the white light of the cured films of Example 1 and Comparative Examples 1 to 4.

Claims (13)

A method for manufacturing a dispersion of spherical alumina particles, which is a method for manufacturing a dispersion of spherical alumina particles comprising spherical alumina particles, a dispersant and a solvent, and comprising: Disperse the liquid containing raw alumina particles, dispersant, and solvent together with beads with an average particle diameter of less than 0.10 mm, so that the spherical alumina particles are substantially reduced from an average particle diameter of 1 to 10 μm. The step of dispersing the raw alumina particles in a manner formed by spherical alumina particles; The raw alumina particles are used as the raw materials for the spherical alumina particles, and the dispersant includes at least one selected from the group consisting of nonionic dispersants and cationic dispersants. The method for producing a dispersion of spherical alumina particles according to claim 1, wherein the dispersant includes a nonionic dispersant and a cationic dispersant. The method for producing a dispersion of spherical alumina particles according to claim 2, wherein the cationic dispersant is an amine polymer dispersant. The method for producing a dispersion of spherical alumina particles according to any one of claims 1 to 3, wherein the average particle size of the raw alumina particles is 1 to 10 μm. A method for manufacturing a coating film forming composition, which includes: The spherical alumina particle dispersion preparation step is to disperse a liquid containing raw alumina particles, a dispersant, and a solvent together with beads with an average particle diameter of less than 0.10 mm, so that the aforementioned spherical alumina particles The raw material alumina particles are dispersed in a way that essentially consists of spherical alumina particles with an average particle size of 1-10 μm. The raw alumina particles are the raw materials for the spherical alumina particles, and the dispersant includes at least one selected from the group consisting of nonionic dispersants and cationic dispersants; and, The coating film forming composition preparation step is a process of adding a coating film forming component to the spherical alumina particle dispersion obtained in the spherical alumina particle dispersion preparation step, and performing agitation treatment. A method for manufacturing hardened film, which includes: The spherical alumina particle dispersion preparation step is to disperse a liquid containing raw alumina particles, a dispersant, and a solvent together with beads with an average particle diameter of less than 0.10 mm, so that the aforementioned spherical alumina particles The raw material alumina particles are dispersed in a way that essentially consists of spherical alumina particles with an average particle size of 1-10 μm. The raw alumina particles are the raw materials for the aforementioned spherical alumina particles, and the dispersant includes at least one selected from the group consisting of non-ionic dispersants and cationic dispersants; A coating film forming composition preparation step, which is to add and mix coating film forming components to the spherical alumina particle dispersion obtained in the spherical alumina particle dispersion preparation step; and, The cured film forming step is to apply the coating film forming composition obtained in the coating film forming composition preparation step to the surface of the substrate to form a coating film, and to harden the coating film to form a cured film. The method for manufacturing a cured film of claim 6, wherein the foregoing cured film is an optical film for improving the viewing angle. A dispersion of spherical alumina particles for improving viewing angle optical films, which contains spherical alumina particles, a dispersant and a solvent. The spherical alumina particles are essentially oxidized from a spherical shape with an average particle diameter of 1-10 μm. In the case of aluminum particles, the dispersant includes at least one selected from a nonionic dispersant and a cationic dispersant. The spherical alumina particle dispersion for improving the viewing angle optical film of claim 8, wherein the aforementioned dispersant includes a nonionic dispersant and a cationic dispersant. A coating film-forming composition for a viewing angle-improving optical film, which comprises the spherical alumina particle dispersion for a viewing angle-improving optical film and a coating film-forming component as claimed in Claim 8 or 9. The composition for forming a coating film for a viewing angle improvement optical film as claimed in claim 10, which contains alcohols. A viewing angle improvement optical film, which is a cured film of the coating film forming composition for a viewing angle improvement optical film as claimed in claim 10 or 11. For example, the improved viewing angle optical film of claim 12, in which the ratio of the transmittance of white light at a wavelength of 900nm to a wavelength of 350nm (900nm/350nm) is less than 3.10, The penetrating light intensity of the white light at an incident angle of 0° relative to the surface of the cured film is 2900 or more, and the penetrating light intensity of the white light at the aforementioned incident angle of 5° is 430 or more.

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