Powder, filler, composition, and method for producing filler

Abstract

To provide a powder having a high transmittance, which is suitable as a filler for an optical material or a resin required to have transparency.SOLUTION: A powder according to the present invention comprises crystalline plate-like titanium phosphate particles, in which the ratio of particles having a particle diameter of 0.52 μm or more and 0.87 μm or less is 7.0 mass% or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a powder, a filler, a composition, and a method for producing the filler. [Background technology]

[0002] Powders with high transmittance are required as fillers for optical materials and resins that require transparency. Patent Document 1 describes inorganic oxide particles useful for incorporation into light scatterers (sheets), which are formed of a core primarily composed of silica and a coating layer of a silica-based composite oxide primarily composed of silica and an oxide of a metal from Group 4 or 14 of the periodic table other than silicon. The inorganic oxide particles have an average particle size of 1.1 to 10 μm and a circularity of 0.8 or greater as determined from an image taken with an electron microscope. The coating layer has a thickness of 0.03 μm or greater and contains 22 to 70 mol % of an oxide of a metal from Group 4 or 14 of the periodic table other than silicon.

[0003] Patent Document 2 describes the use of a filler consisting of at least one selected from titanium oxide, aluminum oxide, zirconium oxide, cerium oxide, and barium titanate and having an average particle size of 0.5 to 50 μm, with the aim of providing a light extraction resin composition that can sufficiently increase the light extraction efficiency of a light-emitting device, in particular a light extraction resin composition that can form a light extraction layer that adheres with high adhesive strength to a transparent substrate of a light-emitting device and is capable of extracting light highly efficiently.

[0004] Patent Document 3 describes a film that is made of a layered substance and an organic substance, contains 0.1% by mass to 15% by mass of the organic substance between the layers of the layered substance, and contains 0.01% by mass to 80% by mass of intercalation compound particles having an average particle size of 5 μm or less and a proportion of coarse particles of 10 μm or more of 10% by mass or less, with the aim of providing a film containing intercalation compound particles that have excellent adhesion at the interface with a matrix polymer. Note that an intercalation compound is a compound in which an organic substance exists between the layers of a layered substance.

[0005] Patent Document 3 also describes that methods for obtaining a layered compound with a fine particle size include methods using ordinary grinding and sizing methods, that the intercalation compound obtained by synthesis is likely to yield fine particles, and that the particle shape of the intercalation compound particles may be any shape such as spherical, plate-like, or irregular, but that particles as close to spherical as possible are preferable. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 4841880 [Patent Document 2] Patent No. 6269669 [Patent Document 3] Patent No. 3250219 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a powder with high transmittance that is suitable as a filler for optical materials and resins that require transparency. [Means for solving the problem]

[0008] In order to solve the above problems, a first aspect of the present invention provides a powder made of crystalline plate-like titanium phosphate particles, in which the proportion of particles having a particle size of 0.52 μm or more and 0.87 μm or less is 7.0 mass % or less. A second aspect of the present invention provides a method for producing a filler consisting of a powder of crystalline plate-like titanium phosphate particles, which method includes a step of confirming that the proportion of particles having a particle size of 0.52 μm or more and 0.87 μm or less in the powder is 7.0 mass% or less. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a powder with high transmittance that is suitable as a filler for optical materials and resins that require transparency. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a graph showing the relationship between the total light transmittance and the volume-based cumulative 50% primary particle size of synthetic products A to F. [Figure 2] 1 is a graph showing the relationship between the total light transmittance of Samples Nos. 1 to 9 and the proportion of particles having a particle size of 0.52 μm or more and 0.87 μm or less. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments. In the following embodiments, technically preferable limitations are imposed for carrying out the present invention, but these limitations are not essential requirements for the present invention. The filler of this embodiment is a powder of crystalline plate-like titanium phosphate particles, and the proportion of particles with a particle size of 0.52 μm to 0.87 μm in this powder is 7.0 mass % or less. The aspect ratio of the crystalline plate-like titanium phosphate particles is 5 or more.

[0012] Using image analysis, the longest diagonal line on the plate surface of the plate crystal can be measured as the primary particle diameter, and the volume-based cumulative 50% primary particle diameter (volume D50% diameter) can be calculated. Furthermore, using image analysis, the thickness of the side surface of the plate crystal can be measured, and the volume-based cumulative 50% thickness (volume D50% thickness) can be calculated. The aspect ratio is the value obtained by dividing the volume D50% diameter by the volume D50% thickness. This filler can be obtained, for example, by the following method.

[0013] First, a titanyl sulfate aqueous solution and a phosphoric acid aqueous solution are mixed in a ratio such that the ratio of the molar concentration of phosphorus [P] to the molar concentration of titanium [Ti], [P] / [Ti], is 5 or more and 21 or less to obtain a mixed solution. Next, this mixed solution is placed in a sealed container, and the temperature is maintained within a range of 100°C to 160°C, and the mixture is allowed to react for a predetermined time (e.g., 5 hours or more). In other words, hydrothermal synthesis is performed. The pressure inside the sealed container is set to a pressure equal to or greater than atmospheric pressure, which is naturally determined by the pressurization temperature. This produces a slurry containing titanium phosphate crystal particles.

[0014] Next, the resulting slurry is cooled, and the solid matter (titanium phosphate crystal particles) is separated from the slurry. The resulting solid matter is washed with a cleaning solution consisting of water or ammonia water (ammonium hydroxide), and then dried. This yields a powder of crystalline plate-like titanium phosphate. Next, the particle size distribution of the obtained crystalline plate-like titanium phosphate powder is measured, and if the proportion of particles with a particle size of 0.52 μm or more and 0.87 μm or less is 7.0 mass% or less, the total light transmittance is expected to be high, and the powder can be used as is as a filler.

[0015] If the particle size distribution of the obtained crystalline plate-like titanium phosphate powder shows that the proportion of particles with a particle size of 0.52 μm or more and 0.87 μm or less exceeds 7.0 mass%, crystalline plate-like titanium phosphate powders with different particle size distributions are mixed so that the proportion of particles with a particle size of 0.52 μm or more and 0.87 μm or less is 7.0 mass% or less.The crystalline plate-like titanium phosphate powder with the proportion of particles with a particle size of 0.52 μm or more and 0.87 μm or less is then used as a filler.

[0016] That is, the method for producing a filler according to this embodiment is a method for producing a powder of crystalline plate-like titanium phosphate particles, and includes a step of confirming that the proportion of particles with a particle size of 0.52 μm or more and 0.87 μm or less in the powder is 7.0 mass % or less, thereby enabling the production of a filler with high total light transmittance. [Example]

[0017] [Synthesis of titanium phosphate] Six types of titanium phosphates (A to F) were synthesized by the following method. <Synthetic product A> First, a titanyl sulfate solution and a phosphoric acid solution were mixed in a ratio of 9.0 (the molar concentration of titanium [Ti] to the molar concentration of phosphorus [P]) to obtain a mixed solution. Next, this mixed solution was placed in a 1.4 L autoclave, and the temperature was maintained at 110°C for 5 hours to react.

[0018] After the reaction, the lid was opened and the slurry in the container was cooled to room temperature, then removed from the container and filtered to separate the solid matter from the slurry. The solid matter was washed with water and then dried (at 105°C for 24 hours) to obtain a powder. The obtained powder was analyzed using an X-ray diffraction device, and it was confirmed that the particles constituting the powder were crystalline titanium phosphate with the structural formula Ti(HPO4)2·H2O. When the obtained powder was observed under a scanning electron microscope, it was confirmed that the particles constituting the powder were plate-like, with many of them being hexagonal plate-like.

[0019] The scanning electron microscope images were analyzed using the image analysis software "Mac-View ver.4" manufactured by Mountech Co., Ltd., and the volume D50% diameter, CV value (standard deviation / number average primary particle diameter), and volume D50% thickness of the crystal particles constituting the obtained powder were measured. The volume D50% diameter was 0.29 μm, the CV value was 0.45, and the volume D50% thickness was 0.030 μm. Furthermore, the aspect ratio of the crystal grains constituting the obtained powder was 10, calculated (0.29 / 0.030) using the measured values ​​of the volume D50% thickness and volume D50% diameter. Furthermore, when the same analysis software was used to examine the proportion of particles with particle sizes in the range of 0.52 μm to 0.87 μm, it was found to be 5.82 mass %.

[0020] The total light transmittance was measured by the following method and was found to be 89.5%. First, the powder was dispersed in a cyclopentasiloxane solution of acrylates / dimethicone copolymer (KP-545, manufactured by Shin-Etsu Chemical Co., Ltd.) to prepare a 10% by mass slurry. This slurry was then applied to a 1 mm thick glass slide to form a 25 μm thick coating, which was then dried to obtain a test sample. The resulting test sample was then measured for total light transmittance under Illuminant C in accordance with ASTM Standard D 1003 using a haze meter "Hazeguard i" manufactured by BYK Japan.

[0021] <Synthetic product B> First, a titanyl sulfate solution and a phosphoric acid solution were mixed in a ratio of 10.7 (the molar concentration of titanium [Ti] to the molar concentration of phosphorus [P]) [P] / [Ti] to obtain a mixed solution. Next, this mixed solution was placed in a 1.4 L autoclave, and the temperature was maintained at 110°C to react for 5 hours. After the reaction, the lid was opened and the slurry in the container was cooled to room temperature, then removed from the container and filtered to separate the solid matter from the slurry. The solid matter was washed with water and then dried (at 105°C for 24 hours) to obtain a powder.

[0022] The obtained powder was analyzed using an X-ray diffraction device, and it was confirmed that the particles constituting the powder were crystalline titanium phosphate with the structural formula Ti(HPO4)2·H2O. When the obtained powder was observed under a scanning electron microscope, it was confirmed that the particles constituting the powder were plate-shaped, with many hexagonal plate-shaped particles. Furthermore, when the volume D50% diameter, CV value (standard deviation / number average primary particle diameter), and volume D50% thickness of the crystal particles constituting the obtained powder were measured using the same method as for synthetic product A, the volume D50% diameter was 0.53 μm, the CV value was 0.34, and the volume D50% thickness was 0.065 μm.

[0023] Furthermore, the aspect ratio of the crystal particles constituting the obtained powder was 8, calculated (0.53 / 0.065) using the measured values ​​of the volume D50% thickness and volume D50% diameter. Furthermore, when the proportion of particles with particle sizes in the range of 0.52 μm or more and 0.87 μm or less was examined using the same method as for synthetic product A, it was found to be 72.64 mass %. Furthermore, when the total light transmittance was measured using the same method as for synthetic product A, it was 85.1%.

[0024] <Synthetic product C> First, a titanyl sulfate solution and a phosphoric acid solution were mixed in a ratio of 10.4 (P / Ti), where P is the molar concentration of phosphorus and Ti is the molar concentration of titanium. Next, this mixture was placed in a 1.4 L autoclave and reacted for 5 hours at 110°C. After the reaction, the lid was opened and the slurry in the container was cooled to room temperature, then removed from the container and filtered to separate the solid matter from the slurry. The solid matter was washed with water and then dried (at 105°C for 24 hours) to obtain a powder.

[0025] The obtained powder was analyzed using an X-ray diffraction device, and it was confirmed that the particles constituting the powder were crystalline titanium phosphate with the structural formula Ti(HPO4)2·H2O. When the obtained powder was observed under a scanning electron microscope, it was confirmed that the particles constituting the powder were plate-shaped, with many hexagonal plate-shaped particles. Furthermore, when the volume D50% diameter, CV value (standard deviation / number average primary particle diameter), and volume D50% thickness of the crystal particles constituting the obtained powder were measured using the same method as for Synthetic Product A, the volume D50% diameter was 0.74 μm, the CV value was 0.42, and the volume D50% thickness was 0.090 μm.

[0026] Furthermore, the aspect ratio of the crystal particles constituting the obtained powder was 8, calculated (0.74 / 0.090) using the measured values ​​of the volume D50% thickness and volume D50% diameter. Furthermore, when the proportion of particles having a particle size in the range of 0.52 μm or more and 0.87 μm or less was examined using the same method as for synthetic product A, it was found to be 67.10 mass %. Furthermore, when the total light transmittance was measured using the same method as for synthetic product A, it was 85.4%.

[0027] <Synthetic product D> First, a titanyl sulfate solution and a phosphoric acid solution were mixed in a ratio of 10.2 (P / Ti), where P is the molar concentration of phosphorus and Ti is the molar concentration of titanium. Next, this mixture was placed in a 200 L autoclave and reacted for 5 hours at 110°C. After the reaction, the lid was opened and the slurry in the container was cooled to room temperature, then removed from the container and filtered to separate the solid matter from the slurry. The solid matter was washed with 29% aqueous ammonia (aqueous solution of ammonium salt) and then dried (at 105°C for 24 hours) to obtain a powder. The obtained powder was analyzed using an X-ray diffraction device, and it was confirmed that the particles constituting the powder were crystalline titanium phosphate with the structural formula Ti(HPO4)2·H2O.

[0028] When the obtained powder was observed under a scanning electron microscope, it was confirmed that the particles constituting the powder were plate-shaped, with many hexagonal plate-shaped particles. Furthermore, when the volume D50% diameter, CV value (standard deviation / number average primary particle diameter), and volume D50% thickness of the crystal particles constituting the obtained powder were measured using the same method as for synthetic product A, the volume D50% diameter was 1.11 μm, the CV value was 0.33, and the volume D50% thickness was 0.143 μm. Furthermore, the aspect ratio of the crystal particles constituting the obtained powder was 8, calculated (1.11 / 0.143) using the measured values ​​of the volume D50% thickness and volume D50% diameter. Furthermore, when the proportion of particles with particle sizes in the range of 0.52 μm or more and 0.87 μm or less was examined using the same method as for synthetic product A, it was found to be 16.97 mass %. Furthermore, when the total light transmittance was measured using the same method as for synthetic product A, it was 87.1%.

[0029] <Synthetic product E> First, a titanyl sulfate solution and a phosphoric acid solution were mixed in a ratio of 6.9 (P / Ti), where P is the molar concentration of phosphorus and Ti is the molar concentration of titanium. Next, this mixture was placed in a 1.4 L autoclave and reacted for 5 hours at 120°C. After the reaction, the lid was opened and the slurry in the container was cooled to room temperature, then removed from the container and filtered to separate the solid matter from the slurry. The solid matter was washed with water and then dried (at 105°C for 24 hours) to obtain a powder.

[0030] The obtained powder was analyzed using an X-ray diffraction device, and it was confirmed that the particles constituting the powder were crystalline titanium phosphate with the structural formula Ti(HPO4)2·H2O. When the obtained powder was observed under a scanning electron microscope, it was confirmed that the particles constituting the powder were plate-shaped, with many hexagonal plate-shaped particles. Furthermore, when the volume D50% diameter, CV value (standard deviation / number average primary particle diameter), and volume D50% thickness of the crystal particles constituting the obtained powder were measured using the same method as for Synthetic Product A, the volume D50% diameter was 2.07 μm, the CV value was 0.37, and the volume D50% thickness was 0.302 μm.

[0031] Furthermore, the aspect ratio of the crystal particles constituting the obtained powder was 7, calculated using the measured values ​​of the volume D50% thickness and volume D50% diameter (2.07 / 0.302). Furthermore, when the proportion of particles having a particle size in the range of 0.52 μm or more and 0.87 μm or less was examined using the same method as for synthetic product A, it was found to be 1.05 mass %. Furthermore, when the total light transmittance was measured using the same method as for synthetic product A, it was 90.3%.

[0032] <Synthetic product F> First, a titanyl sulfate solution and a phosphoric acid solution were mixed in a ratio of 10.8 (the molar concentration of titanium [Ti] to the molar concentration of phosphorus [P]) [P] / [Ti] to obtain a mixed solution. Next, this mixed solution was placed in a 200 L autoclave, and the temperature was maintained at 130°C to react for 5 hours. After the reaction, the lid was opened and the slurry in the container was cooled to room temperature, then removed from the container and filtered to separate the solid matter from the slurry. The solid matter was washed with water and then dried (at 105°C for 24 hours) to obtain a powder.

[0033] The obtained powder was analyzed using an X-ray diffraction device, and it was confirmed that the particles constituting the powder were crystalline titanium phosphate with the structural formula Ti(HPO4)2·H2O. When the obtained powder was observed under a scanning electron microscope, it was confirmed that the particles constituting the powder were plate-shaped, with many hexagonal plate-shaped particles. Furthermore, when the volume D50% diameter, CV value (standard deviation / number average primary particle diameter), and volume D50% thickness of the crystal particles constituting the obtained powder were measured using the same method as for Synthetic Product A, the volume D50% diameter was 7.44 μm, the CV value was 0.36, and the volume D50% thickness was 0.856 μm.

[0034] Furthermore, the aspect ratio of the crystal particles constituting the obtained powder was 9, calculated (7.44 / 0.856) using the measured values ​​of the volume D50% thickness and volume D50% diameter. Furthermore, when the proportion of particles with particle sizes in the range of 0.52 μm or more and 0.87 μm or less was examined using the same method as for synthetic product A, it was found to be 0.00 mass %. Furthermore, when the total light transmittance was measured using the same method as for synthetic product A, it was 91.4%. The relationship between the total light transmittance and the volume-based cumulative 50% primary particle diameter (volume D50% diameter) of the synthesized titanium phosphate powders A to F is shown in the graph in Figure 1. The graph in Figure 1 shows that the total light transmittance reaches its minimum value when the volume D50% diameter is around 0.53 μm and 0.74 μm.

[0035] [Powder preparation] The synthesized titanium phosphate powders A to F were mixed in the proportions shown in Table 1 below to obtain titanium phosphate powders No. 1 to No. 9. Titanium phosphate powders No. 1 to No. 6 are the same as the synthesized titanium phosphate powders A to D, respectively. Because titanium phosphate powders No. 7 to No. 9 are mixtures, the volume D50% diameter, CV value, and volume D50% thickness were measured using the methods described above, and the aspect ratio was calculated. Furthermore, the proportion of particles with particle sizes in the range of 0.52 μm to 0.87 μm was determined using the same method as for synthesized product A, and the total light transmittance was measured using the same method as for synthesized product A. The composition of each powder, the proportion of particles with a particle size in the range of 0.52 μm to 0.87 μm, the volume D50% diameter, CV value, volume D50% thickness, aspect ratio, and total light transmittance are shown in Table 1. The relationship between the total light transmittance and the proportion of particles with a particle size in the range of 0.52 μm to 0.87 μm for Samples No. 1 to 9 is shown in a graph in Figure 2.

[0036] [Table 1]

[0037] The results reveal the following: The total light transmittance of powders No. 1, No. 5, No. 6, and No. 9, which consist of crystalline plate-like titanium phosphate particles and have a particle content of 5.82 mass% or less with a particle size range of 0.52 μm or more and 0.87 μm or less, was high at 89.5% or more and 91.4% or less.However, the total light transmittance of powders No. 2 to No. 4, No. 7, and No. 8, which have a particle content of 7.22 mass% or more with a particle size range of 0.52 μm or more and 0.87 μm or less, was low at 84.1% or more and 87.1% or less.

[0038] Therefore, powders with a content of particles having a particle size in the range of 0.52 μm to 0.87 μm of 5.82 mass % or less (7.0 mass % or less) can be said to be suitable as optical materials and resin fillers that require transparency. Furthermore, by including a step of confirming that "the powder consisting of crystalline plate-like titanium phosphate particles contains 7.0 mass% or less of particles with particle sizes in the range of 0.52 μm or more and 0.87 μm or less," the method for producing titanium phosphate powder for fillers can produce titanium phosphate powder suitable for use as a filler in optical materials and resins that require transparency.

Claims

1. A filler for optical materials and resins, which is made of a powder of crystalline plate-like titanium phosphate particles, in which the proportion of particles with a particle size of 0.52 μm or more and 0.87 μm or less is 7.0 mass % or less, and which has a total light transmittance of 89.5% or more when using light source C in accordance with ASTM standard "D 1003".

2. A composition comprising the filler of claim 1.

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