Abstract: A method for producing an optical material includes a predetermined compound (a), compound (b), compound (c), compound (d), and compound (e). The method minimizes the occurrence of a defect where peeling traces are left on a lens. The first to the fifth step minimizes the defect where peeling traces are left. First: dissolving the compound (b) into the compound (a) to obtain a first solution. Second: adding the compound (e) to the first solution obtained in the first step and then mixing to obtain a second solution not comprising the compound (d). Third: adding the compound (c) to the second solution obtained in the second step to obtain a reaction mixture. Fourth: adding the compound (d) to the reaction mixture obtained in the third step and then mixing to obtain a resin composition for an optical material. Fifth: cast-molding the resin composition and then polymerizing to obtain the optical material.

Abstract: The present invention provides a vehicle transmission having excellent sliding properties over the entire speed range of engines from a low speed range to a high speed range. The present invention is a vehicle transmission oil seal comprising: an elastic member with a seal lip portion having at least a main lip portion, wherein the elastic member is formed of a composition containing a fluororubber and a fluororesin and has projecting portions at least on a surface of the main lip portion, the projecting portions being substantially formed of the fluororesin contained in the composition, the fluororesin is a copolymer including a polymerization unit derived from ethylene and a polymerization unit derived from tetrafluoroethylene, and the fluororubber is a polymer including a polymerization unit derived from vinylidene fluoride.

Abstract: The present invention has an object of providing, for example, a composition for optical materials which contains a polythiol that can be predicted and assessed, in a stage prior to polymerization/curing, as being clouded or not clouded after polymerization/curing, and thus can be determined as being good or defective. According to the present invention, the above-described object is achieved by, for example, a composition for optical materials which comprises a polythiol that exhibits an initial turbidity of 0.5 ppm or less and a turbidity of 0.6 ppm or less after the storage at 50° C. for 7 days, and an episulfide. Namely, an optical material made from a composition for optical materials which contains a polythiol satisfying the above turbidity requirements can be prevented from clouding to exhibit excellent transparency.

Abstract: The present invention has an object of providing, for example, a composition for optical materials which contains a polythiol that can be predicted and assessed, in a stage prior to polymerization/curing, as being clouded or not clouded after polymerization/curing, and thus can be determined as being good or defective. According to the present invention, the above-described object is achieved by, for example, a composition for optical materials which comprises a polythiol that exhibits an initial turbidity of 0.5 ppm or less and a turbidity of 0.6 ppm or less after the storage at 50° C. for 7 days, and an episulfide. Namely, an optical material made from a composition for optical materials which contains a polythiol satisfying the above turbidity requirements can be prevented from clouding to exhibit excellent transparency.

Abstract: The present invention provides a vehicle valve stem seal having both durability and sliding properties at an extremely high level in addition to usual sealing performance. The present invention is a vehicle valve stem seal comprising an elastic member with a seal lip portion on an end of a valve stem guide, the seal lip portion slidably closely contacting with a valve stem of an engine, wherein the elastic member is formed of a composition containing a fluororubber and a fluororesin and has projecting portions at least on a surface of the seal lip portion, the projecting portions being substantially formed of the fluororesin contained in the composition, the fluororesin is a copolymer including a polymerization unit derived from ethylene and a polymerization unit derived from tetrafluoroethylene, and the fluororubber is a polymer including a polymerization unit derived from vinylidene fluoride.

Abstract: A method for producing an optical material includes a predetermined compound (a), compound (b), compound (c), compound (d), and compound (e). The method minimizes the occurrence of a defect where peeling traces are left on a lens. The first to the fifth step minimizes the defect where peeling traces are left. First: dissolving the compound (b) into the compound (a) to obtain a first solution. Second: adding the compound (e) to the first solution obtained in the first step and then mixing to obtain a second solution not comprising the compound (d). Third: adding the compound (c) to the second solution obtained in the second step to obtain a reaction mixture. Fourth: adding the compound (d) to the reaction mixture obtained in the third step and then mixing to obtain a resin composition for an optical material. Fifth: cast-molding the resin composition and then polymerizing to obtain the optical material.

Abstract: Provided is a cross-linkable fluororubber composition capable of giving a fluororubber cross-linked molded article that has excellent mechanical strength and low friction properties. The cross-linkable fluororubber composition includes a coagulum obtained by co-coagulating a fluororubber (A) and a fluororesin (B).

Abstract: A fluororubber molded article produced by crosslinking a crosslinkable composition containing a fluororubber (A) and a fluororesin (B), wherein the fluororubber molded article has a surface with projecting portions, an area ratio of areas having the projecting portions to the entire surface of the fluororubber molded article is not less than 0.06, a volume ratio of the fluororesin (B) to the fluororubber molded article is 0.05 to 0.45, the area ratio of the areas having the projecting portions is 1.2 times or more larger than the volume ratio of the fluororesin (B), and the fluororesin (B) is a tetrafluoroethylene/hexafluoropropylene copolymer.

Abstract: The present invention relates to a composition for an optical material, which is capable of suppressing occurrence of polymerization unevenness called striae, in particular, striae to be caused in high-powered lenses with sharp curves, and more specifically relates to a composition for an optical material including: a polymerization catalyst having a mass ratio of dibutyltin dichloride to monobutyltin trichloride of 97.0/3.0 to 100.0/0.0; a polythiol compound; and a polyiso(thio)cyanate compound.

Abstract: The present invention relates to a composition for an optical material capable of suppressing generation of inhomogeneity called “stria” in polymerization, in particular, generation of striae in a lens having high optical power or a surface with high radius of curvature, and more specifically relates to a composition for an optical material, comprising: a stabilizer having a mass ratio of dibutyltin dichloride to monobutyltin trichloride of 97.0/3.0 to 100.0/0.0; an episulfide compound; a polythiol compound; and a polymerization catalyst for the episulfide compound.

Abstract: The present invention provides a vehicle valve stem seal having both durability and sliding properties at an extremely high level in addition to usual sealing performance. The present invention is a vehicle valve stem seal comprising an elastic member with a seal lip portion on an end of a valve stem guide, the seal lip portion slidably closely contacting with a valve stem of an engine, wherein the elastic member is formed of a composition containing a fluororubber and a fluororesin and has projecting portions at least on a surface of the seal lip portion, the projecting portions being substantially formed of the fluororesin contained in the composition, the fluororesin is a copolymer including a polymerization unit derived from ethylene and a polymerization unit derived from tetrafluoroethylene, and the fluororubber is a polymer including a polymerization unit derived from vinylidene fluoride.

Abstract: The present invention has an object of providing, for example, a composition for optical materials which contains a polythiol that can be predicted and assessed, in a stage prior to polymerization/curing, as being clouded or not clouded after polymerization/curing, and thus can be determined as being good or defective. According to the present invention, the above-described object is achieved by, for example, a composition for optical materials which comprises a polythiol that exhibits an initial turbidity of 0.5 ppm or less and a turbidity of 0.6 ppm or less after the storage at 50° C. for 7 days, and an episulfide. Namely, an optical material made from a composition for optical materials which contains a polythiol satisfying the above turbidity requirements can be prevented from clouding to exhibit excellent transparency.

Abstract: The present invention provides a vehicle transmission having excellent sliding properties over the entire speed range of engines from a low speed range to a high speed range. The present invention is a vehicle transmission oil seal comprising: an elastic member with a seal lip portion having at least a main lip portion, wherein the elastic member is formed of a composition containing a fluororubber and a fluororesin and has projecting portions at least on a surface of the main lip portion, the projecting portions being substantially formed of the fluororesin contained in the composition, the fluororesin is a copolymer including a polymerization unit derived from ethylene and a polymerization unit derived from tetrafluoroethylene, and the fluororubber is a polymer including a polymerization unit derived from vinylidene fluoride.

Abstract: The present invention provides a vehicle engine oil seal having excellent sliding properties over the entire rotation range of engines from a low rotation range to a high rotation range. The present invention is a vehicle engine oil seal comprising: an elastic member with a seal lip portion having at least a main lip portion, wherein the elastic member is formed of a composition containing a fluororubber and a fluororesin and has projecting portions at least on a surface of the main lip portion, the projecting portions being substantially formed of the fluororesin contained in the composition, the fluororesin is a copolymer including a polymerization unit derived from ethylene and a polymerization unit derived from tetrafluoroethylene, and the fluororubber is a polymer including a polymerization unit derived from vinylidene fluoride.

Abstract: Provided is a cross-linkable fluororubber composition capable of giving a fluororubber cross-linked molded article that has excellent mechanical strength and low friction properties. The cross-linkable fluororubber composition includes a coagulum obtained by co-coagulating a fluororubber (A) and a fluororesin (B).

Abstract: A golf ball (1) comprises a core (3) and a cover (5). The core (3) has a six-layer structure having first to sixth layers (7) to (17). A value of (T1/T2) is greater than 2.10 and is equal to or smaller than 2.50, wherein time series data on force in a z direction which is applied to a load cell provided on a back face of a collision plate inclined by 22 degrees with respect to a horizontal direction when the golf ball (1) impacts the collision plate at a speed of 35 m/s in a vertically upward direction are represented by Fn(t), time series data on force in an x direction are represented by Ft(t), a time taken after a start of the impact before the Fn(t) is first changed from a positive number to zero is represented by T1 and a time taken after the start of the impact before the Ft(t) is first changed from a positive number to a negative number is represented by T2. The golf ball (1) has a higher back spin rate during hitting on the same conditions than that of a conventional golf ball.

Abstract: A golf ball (1) comprises a core (3) and a cover (5). The core (3) has a six-layer structure having first to sixth layers (7) to (17). A value of (T1/T2) is greater than 2.10 and is equal to or smaller than 2.50, wherein time series data on force in a z direction which is applied to a load cell provided on a back face of a collision plate inclined by 22 degrees with respect to a horizontal direction when the golf ball (1) impacts the collision plate at a speed of 35 m/s in a vertically upward direction are represented by Fn(t), time series data on force in an x direction are represented by Ft (t), a time taken after a start of the impact before the Fn(t) is first changed from a positive number to zero is represented by T1 and a time taken after the start of the impact before the Ft (t) is first changed from a positive number to a negative number is represented by T2. The golf ball (1) has a higher backspin rate during hitting on the same conditions than that of a conventional golf ball.

Abstract: A multi-piece solid golf ball has rebound characteristics equal to conventional two-piece solid golf ball when hitting at high head speed, and better rebound characteristics when hitting at low head speed. This multi-piece solid golf ball has a core with an inner layer outer layer on the inner layer, and at least one layer of cover on the core, the inner layer core having an elastic modulus of 50 to 200 MPa, the outer layer core having at least one layer of low elastic modulus with elastic modulus lower than the inner layer core by 15 to 100 MPa; at least one layer of the lowest elastic modulus layer in the core has a total thickness of 0.2 to 5.0 mm and is placed from 6.5 to 20.5 mm away from the core center point with diameter 37 to 41 mm.

Abstract: A golf ball (1) comprises a core (3) and a cover (5). The core (3) has a six-layer structure having first to sixth layers (7, 9, 11, 13, 15, 17). An inner layer of the core 3 has a low modulus of elasticity. To the contrary, an outer layer of the core (3) has a high modulus of elasticity. If time series data on force in a z direction which is applied to a load cell provided on a back face of a collision plate inclined by 22 degrees with respect to a horizontal direction when the golf ball (1) impacts with the collision plate at a speed of 35 m/s in a vertical upward direction are represented by Fn(t), time series data on force in an x direction are represented by Ft(t) and a time taken after a start of the impact before the Fn(t) is first changed from a positive number to zero is represented by T1 and a time taken after the start of the impact before the Ft(t) is first changed from a positive number to a negative number is represented by T2, a value of (T1/T2) is 1.85 to 2.10.

Abstract: Disclosed is a thermoplastic elastomer composition having characteristics of both thermoplastic resin and rubber, and a golf ball using the thermoplastic elastomer composition as the cover. The thermoplastic elastomer composition of the present invention comprises a thermoplastic resin and crosslinked diene rubber particles having an average diameter of not more than 10 .mu.m dispersed in the thermoplastic resin, which is prepared by dynamic crosslinking diene rubber dispersed in the thermoplastic resin with crosslinking agent.