Abstract: Provided is a polyfunctional vinyl aromatic copolymer having reactivity and solubility that can be used for manufacturing a copolymer rubber and a copolymer rubber material having processability, strength and homogeneity obtained therefrom. The polyfunctional vinyl aromatic copolymer includes: 0.5 mol % or more and 40 mol % or less of a structural unit (a) derived from a divinyl aromatic compound and 60 mol % or more and 99.5 mol % or less of a structural unit (b) derived from a monovinyl aromatic compound, in which at least some of the structural units (a) are a crosslinked structural unit (a2) represented by the following Formula (2) and a vinyl-group-containing structural unit (a1) represented by the following Formula (1): in the formulas, R1's independently represent an aromatic hydrocarbon group having 6 to 30 carbon atoms.

Abstract: To provide a modified vinylaromatic copolymer which can be used in production of copolymer rubber and which has reactivity and solubility, and a copolymer rubber material obtained therefrom, which simultaneously has processability, strength, and homogeneity. The modified vinylaromatic copolymer is a copolymer containing a structural unit (a) derived from a divinylaromatic compound and a structural unit (b) derived from a monovinylaromatic compound, wherein the structural unit (a) at least partially includes the following crosslinked structural unit (a1), and a terminal is modified by a modification group having at least one functional group selected from the group consisting of an amino group, a hydroxyl group, and an alkoxysilyl group.

Abstract: Provided is a polyfunctional vinyl aromatic copolymer having reactivity and solubility that can be used for manufacturing a copolymer rubber and a copolymer rubber material having processability, strength and homogeneity obtained therefrom. The polyfunctional vinyl aromatic copolymer includes: 0.5 mol % or more and 40 mol % or less of a structural unit (a) derived from a divinyl aromatic compound and 60 mol % or more and 99.5 mol % or less of a structural unit (b) derived from a monovinyl aromatic compound, in which at least some of the structural units (a) are a crosslinked structural unit (a2) represented by the following Formula (2) and a vinyl-group-containing structural unit (a1) represented by the following Formula (1): in the formulas, R1's independently represent an aromatic hydrocarbon group having 6 to 30 carbon atoms.

Abstract: Provided are a lubricating oil base oil having characteristics of low volatility and excellent low-temperature fluidity and capable of providing long-lasting lubrication property in a wide temperature range from low temperature to high temperature, and a lubricating oil composition using the same. The lubricating oil base oil includes a diester obtained through a reaction between a diol component formed of 1,12-dodecanediol and a carboxylic acid component formed of 2-methylpentanoic acid or 2-methylpentanoic acid and 2-ethylhexanoic acid. The diester is represented by R2COOR1OOCR3, where R1 represents an alkylene derived from the diol component and R2 and R3 each represent an alkyl derived from the carboxylic acid component, and includes 45 to 100 mol % of a diester in which both of R2 and R3 represent C5 alkyls.

Abstract: A lubricating oil base oil includes, as a major component, a diester represented by the following formula (1), and a lubricating oil composition including the lubricating oil base oil. In the formula, R1 and R2 each independently represent a 1-ethylpentyl group, an n-heptyl group, or a n-hexyl group. When the diester in which both of R1 and R2 each represent an n-heptyl group or an n-hexyl group is defined as A, the diester in which one of R1 and R2 represents a 1-ethylpentyl group is B, and the diester in which both of R1 and R2 each represent a 1-ethylpentyl group is defined as C, the molar ratio of the diesters falls within a range of A:B:C=25 to 65:30 to 50:3 to 25. The lubricating oil base oil is suitable for a fluid dynamic pressure bearing, an oil-impregnated porous bearing, or a dynamic pressure-type oil-impregnated porous bearing.

Abstract: Provided are a lubricating oil base oil excellent in durability and low-torque property, and a lubricating oil composition suitable for a fluid dynamic pressure bearing, an oil-impregnated porous bearing, or a dynamic pressure-type oil-impregnated porous bearing to be used in a bearing for a small spindle motor related to information equipment. Specifically, provided are a lubricating oil base oil including, as a major component, a diester represented by the following formula (1), and a lubricating oil composition including the lubricating oil base oil.

Abstract: Provided are a lubricating oil base oil having characteristics of low volatility and excellent low-temperature fluidity and capable of providing long-lasting lubrication property in a wide temperature range from low temperature to high temperature, and a lubricating oil composition using the same. The lubricating oil base oil includes a diester obtained through a reaction between a diol component formed of 1,12-dodecanediol and a carboxylic acid component formed of 2-methylpentanoic acid or 2-methylpentanoic acid and 2-ethylhexanoic acid. The diester is represented by R2COOR1OOCR3, where R1 represents an alkylene derived from the diol component and R2 and R3 each represent an alkyl derived from the carboxylic acid component, and includes 45 to 100 mol % of a diester in which both of R2 and R3 represent C5 alkyls.

Abstract: Disclosed is lubricant base oil that is excellent in lubricity, sludge solubility, low viscosity, and low temperature characteristics and capable of realizing low volatility. The lubricant base oil contains as its main component a diester or triester synthesized from a divalent or trivalent carboxylic acid of 9 or less carbon atoms and a monovalent glycol ether such as an alkylene glycol monoalkyl ether of 3 to 25 carbon atoms and is useful as base oil for lubricating oil and grease. Di(hexyloxyethyl) adipate may be cited as an appropriate example of the diester.

Abstract: Disclosed is lubricant base oil that is excellent in lubricity, sludge solubility, low viscosity, and low temperature characteristics and capable of realizing low volatility. The lubricant base oil contains as its main component a diester or triester synthesized from a divalent or trivalent carboxylic acid of 9 or less carbon atoms and a monovalent glycol ether such as an alkylene glycol monoalkyl ether of 3 to 25 carbon atoms and is useful as base oil for lubricating oil and grease. Di(hexyloxyethyl) adipate may be cited as an appropriate example of the diester.