Okayama-shi, Japan
Okayama-shi, Japan

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Patent
Dowa Electronics Materials Co. and Fujifilm Co. | Date: 2016-01-21

A hexagonal ferrite magnetic powder for a magnetic recording medium, containing magnetic powder contains hexagonal ferrite particles having coated on the surface thereof an aluminum hydroxide material, having a Ba/Fe molar ratio of 0.080 or more, a Bi/Fe molar ratio of 0.025 or more, and an Al/Fe molar ratio of from 0.030 to 0.200. The magnetic powder preferably has an activation volume Vact of from 1,300 to 2,000 nm^(3). The magnetic powder particularly preferably has a coercive force Hc of from 159 to 287 kA/m (approximately from 2,000 to 3,600 Oe) and a coercivity distribution SFD of from 0.3 to 1.0. The magnetic powder may contain one or two or more kinds of a divalent transition metal M1 and a tetravalent transition metal M2, as an element that replaces Fe of the hexagonal ferrite. The magnetic powder has improved magnetic characteristics including SNR and durability.


Patent
University of Tokyo and Dowa Electronics Materials Co. | Date: 2016-08-08

An epsilon-type iron oxide having an Fe-site that is substituted with a platinum group element, provided that Fe of a D-site of the epsilon-type iron oxide is not substituted with the platinum group element.


Patent
Dowa Electronics Materials Co. | Date: 2016-03-10

A long-life III nitride semiconductor light emitting device and a method of producing the same. A III nitride semiconductor light-emitting device includes an n-type semiconductor layer; a light emitting layer containing at least Al; and a p-type semiconductor layer obtained by sequentially stacking an electron blocking layer, a p-type cladding layer, and a p-type contact layer, in this order. The electron blocking layer is made of Al_(x)Ga_(1-x)N (0.55x1.0), the p-type contact layer is made of Al_(y)Ga_(1-y)N (0y0.1), the p-type cladding layer is made of Al_(z)Ga_(1-z)N having an Al content z which gradually decreases over the whole thickness of the p-type cladding layer from the electron blocking layer side toward the p-type contact layer side, and the reduction rate of the Al content z of the p-type cladding layer in the thickness direction is 0.01/nm or more and 0.025/nm or less.


A composition containing fine silver particles which have a uniform particle size, can form a fine drawing pattern, and have a small environmental impact, a method for producing that composition, a method for producing fine silver particles, and a paste having fine silver particles are provided. The fine silver particles are produced by carrying out a fluid preparation step of preparing a reduction fluid, a silver reaction step, and a filtration/washing step. The reaction step is carried out by adding an aqueous silver nitrate fluid to a reduction fluid whose temperature has been increased to a range between 40 and 80C. The aqueous silver nitrate fluid is added at a stretch. The composition containing fine silver particles is produced by dispersing the composition containing the fine silver particles in a polar fluid.


Patent
DOWA Electronics Materials Co. | Date: 2016-04-27

A bonding material of a silver paste includes: fine silver particles having an average primary particle diameter of 1 to 50 nanometers, each of the fine silver particles being coated with an organic compound having a carbon number of not greater than 8, such as hexanoic acid; silver particles having an average primary particle diameter of 0.5 to 4 micrometers, each of the silver particles being coated with an organic compound, such as oleic acid; a solvent containing 3 to 7 % by weight of an alcohol and 0.3 to 1% by weight of a triol; a dispersant containing 0.5 to 2 % by weight of an acid dispersant and 0.01 to 0.1 % by weight of phosphate ester dispersant; and 0.01 to 0.1% by weight of a sintering aid, such as diglycolic acid, wherein the content of the fine silver particles is in the range of from 5% by weight to 30% by weight, and the content of the silver particles is in the range of from 60 % by weight to 90% by weight, the content of the total of the fine silver particles and the silver particles being not less than 90 % by weight.


Patent
Dowa Electronics Materials Co. and Dowa IP Creation Co. | Date: 2016-10-05

There are provided ferrite particles that have, as a main component, a material represented by a composition formula M_()Fe_(3-)O_(4) (where M is at least one type of metal selected from a group consisting of Mg, Mn, Ca, Ti, Cu, Zn, Sr and Ni, 0 < < 1), where the maximum height Rz of the particles falls within a range of 1.40 to 1.90, and the degree of distortion Rsk of the particles falls within a range of - 0.25 to - 0.07. In this way, when the ferrite particles are used as the carrier of an electrophotographic image forming apparatus, even if an image formation speed is increased, the occurrence of a failure is reduced for a long period of time.


There is provided a metal nanoparticle dispersion which can be bonded at a lower temperature (for example, 200C or less), and enabling to obtain excellent mechanical properties and electric properties of the bonded portion, the metal nanoparticle dispersion, including: metal nanoparticles, with at least a part of a surface of each particle coated with amine A having 8 or more carbon atoms; and a dispersion medium for dispersing the metal nanoparticles, wherein the dispersion medium contains amine B which is primary, secondary, or tertiary amine having 7 or less carbon atoms, and which is linear alkyl amine or alkanol amine.


Patent
DOWA Electronics Materials Co. | Date: 2016-08-24

A copper particle dispersing solution obtained by dispersing fine copper particles having an average particle diameter of 1 to 100 nm, each of the fine copper particles being coated with an azole compound, such as benzotriazole, and coarse copper particles having an average particle diameter of 0.3 to 20 m in a dispersing medium, such as ethylene glycol, so as to cause the total amount of the fine copper particles and coarse copper particles to be 50 to 90 % by weight and so as to cause the ratio of the weight of the fine copper particles to the weight of the coarse copper particles to be in the range of from 1:9 to 5:5, is applied on a substrate by screen printing or flexographic printing to be preliminary-fired with vacuum drying, and then, fired with light irradiation by irradiating light having a wavelength of 200 to 800 nm at a pulse period of 100 to 3000 m and a pulse voltage of 1600 to 3600 V, to form a conductive film on the substrate.


Patent
DOWA Electronics Materials Co. | Date: 2016-09-21

After there is prepared a conductive paste which contains fine copper particles having an average particle diameter of 1 to 100 nm, each of the fine copper particles being coated with an azole compound, coarse copper particles having an average particle diameter of 0.3 to 20 m, a glycol solvent, such as ethylene glycol, and at least one of a polyvinylpyrrolidone (PVP) resin and a polyvinyl butyral (PVB) resin and wherein the total amount of the fine copper particles and the coarse copper particles is 50 to 90% by weight, the weight ratio of the fine copper particles to the coarse copper particles being in the range of from 1:9 to 5:5, the conductive paste thus prepared is applied on a substrate by screen printing to be preliminary-fired by vacuum drying, and then, fired with light irradiation by irradiating with light having a wavelength of 200 to 800 nm at a pulse period of 500 to 2000 s and a pulse voltage of 1600 to 3800 V to form a conductive film on the substrate.


There are provided ferrite particles in which Mn ferrite is used as the main phase and which contain Sr ferrite, where the degree of projections and recesses in the surface of the particles falls within a range of 2.5 to 4.5 m, and the standard deviation of the size of grains appearing on the surface of the particles falls within a range of 1.5 to 3.5 m. In this way, a coating resin is left on the surface of the particles even after long-term use and thus a decrease in the charging property is reduced.

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