Abstract: A method for producing a glass substrate for a magnetic disk involving the use of a polishing pad having: a first resin foam layer which forms the polishing surface, includes a resin foam having pores with a pore diameter of more than 20 ?m and has a thickness of 400 ?m or less; and a second resin foam layer which is provided between a platen for fixing the polishing pad and the first resin foam layer, includes a resin foam having pores with a pore diameter of 20 ?m or less and has a thickness of 50 to 250 ?m, and in which a total thickness of the first resin foam layer and the second resin foam layer is 550 ?m or less, and a international rubber hardness degree of the polishing pad measured by the M method according to JIS K6253 is 40 IRHD or more.

Abstract: The present invention relates to a method for producing a glass substrate for a magnetic disk, the method including a step of polishing a main surface of a circular glass plate while supplying a polishing slurry containing a polishing material, in which polishing is performed, after a polishing surface is subjected to dressing treatment, by using a polishing pad having: a first resin foam layer which forms the polishing surface, includes a resin foam having pores with a pore diameter of more than 20 ?m and has a thickness of 400 ?m or less; and a second resin foam layer which is provided between a platen for fixing the polishing pad and the first resin foam layer, includes a resin foam having pores with a pore diameter of 20 ?m or less and has a thickness of 50 to 250 ?m, and in which a total thickness of the first resin foam layer and the second resin foam layer is 550 ?m or less, and a international rubber hardness degree of the polishing pad measured by the M method according to JIS K6253 is 40 IRHD or mor

Abstract: In the production of a glass substrate for magnetic disk, the present invention provides a method for producing a glass substrate for magnetic disk including a step of polishing a main surface of a circular glass substrate using a polishing pad made of a foamed resin while feeding a polishing liquid containing an abrasive, in which a polishing pad made of a foamed resin having an international rubber hardness of 45 IRHD or less, the hardness being measured at a dry state before contact with a slurry by the M method defined in JIS K6253, is used as a starting polishing pad and polishing is started after a polishing surface of the starting polishing pad is subjected to a dressing treatment to adjust the pad so that an open pore area ratio is 8% or more and an average circle equivalent diameter of open pores is 10 ?m or more, in order to suppress an increase in roll-off in the polishing step of the main surface of the circular glass plate.

Abstract: The present invention relates to a method for producing a glass substrate for a magnetic disk, the method including a step of polishing a main surface of a circular glass plate while supplying a polishing slurry containing a polishing material, in which polishing is performed, after a polishing surface is subjected to dressing treatment, by using a polishing pad having: a first resin foam layer which forms the polishing surface, includes a resin foam having pores with a pore diameter of more than 20 ?m and has a thickness of 400 ?m or less; and a second resin foam layer which is provided between a platen for fixing the polishing pad and the first resin foam layer, includes a resin foam having pores with a pore diameter of 20 ?m or less and has a thickness of 50 to 250 ?m, and in which a total thickness of the first resin foam layer and the second resin foam layer is 550 ?m or less, and a international rubber hardness degree of the polishing pad measured by the M method according to JIS K6253 is 40 IRHD or mor

Abstract: In the production of a glass substrate for magnetic disk, the present invention provides a method for producing a glass substrate for magnetic disk including a step of polishing a main surface of a circular glass substrate using a polishing pad made of a foamed resin while feeding a polishing liquid containing an abrasive, in which a polishing pad made of a foamed resin having an international rubber hardness of 45 IRHD or less, the hardness being measured at a dry state before contact with a slurry by the M method defined in JIS K6253, is used as a starting polishing pad and polishing is started after a polishing surface of the starting polishing pad is subjected to a dressing treatment to adjust the pad so that an open pore area ratio is 8% or more and an average circle equivalent diameter of open pores is 10 ?m or more, in order to suppress an increase in roll-off in the polishing step of the main surface of the circular glass plate.

Abstract: In the production of a glass substrate for magnetic disks, in a step of polishing a main surface of a circular glass plate, roll-off is reduced without reducing the polishing rate. The process comprises a step of polishing a main surface of a circular glass plate by using an acidic polishing fluid containing colloidal silica or fumed silica, and a water-soluble polymer having at least one member selected from a group consisting of a carboxylic acid group, a carboxylate group, a sulfonic acid group and a sulfonate group, bonded to its main chain, or an acidic polishing fluid containing 100 parts by mass of colloidal silica or fumed silica, and from 0.02 to 0.1 part by mass of a surfactant having a sulfonic acid group.

Abstract: To provide a light-emitting device having an airtight container sealed at a lower temperature by means of a sealing material not containing a harmful component such as lead, which is free from heat deterioration of a phosphor, particularly a blue-emitting phosphor. A light-emitting device having an airtight container sealed by means of a sealing composition comprising a curable methylphenyl silicone resin and a refractory filler, wherein the amount of the refractory filler based on the sum of the methylphenyl silicone resin and the refractory filler in the sealing composition, is from 10 to 80 mass %, and the methylphenyl silicone resin has a molar ratio of phenyl groups to methyl groups (i.e. mols of phenyl groups/mols of methyl groups) of from 0.1 to 1.2.

Abstract: To provide a light-emitting device having an airtight container sealed at a lower temperature by means of a sealing material not containing a harmful component such as lead, which is free from heat deterioration of a phosphor, particularly a blue-emitting phosphor. A light-emitting device having an airtight container sealed by means of a sealing composition comprising a curable methylphenyl silicone resin and a refractory filler, wherein the amount of the refractory filler based on the sum of the methylphenyl silicone resin and the refractory filler in the sealing composition, is from 10 to 80 mass %, and the methylphenyl silicone resin has a molar ratio of phenyl groups to methyl groups (i.e. mols of phenyl groups/mols of methyl groups) of from 0.1 to 1.2.