Abstract: An object of the present disclosure is to provide a golf ball having excellent durability and flight distance and good shot feeling for an average golfer who hits a golf ball at a slow head speed. The present disclosure provides a golf ball comprising a spherical core and at least two cover layers covering the spherical core, wherein a difference between a core surface crosslinking density and a core center crosslinking density is more than 1.0×102 mol/m3 and less than 9.0×102 mol/m3, a hardness difference between a core surface hardness Cs (Shore C hardness) and a core center hardness Co (Shore C hardness) is 13.0 or more and 30.0 or less, a compression deformation amount of the core when applying a load from an initial load of 98 N to a final load of 1275 N to the core is less than 3.

Abstract: A tire includes a tread portion having a ground contacting surface and a first groove. A tread rubber forming the tread portion includes a first rubber layer and a second rubber layer. The second rubber layer has a complex elastic modulus smaller than a complex elastic modulus of the first rubber layer. The first groove includes a first groove edge, a groove bottom surface, and a first groove wall. In a lateral cross section of the first groove, the first groove wall includes a first wide top portion arranged between the first groove edge and the groove bottom surface and located outside the first groove edge in a groove width direction of the first groove. The first wide top portion is positioned in the second rubber layer.

Abstract: An object of the present disclosure is to provide a golf ball having improved flight distance on driver shots and excellent spin performance on approach shots (particularly under the condition that there is grass between the golf ball and the club face) and on middle iron shots. The present disclosure provides a golf ball comprising a spherical core and a cover disposed outside the spherical core, wherein when a center hardness of the spherical core (Shore C hardness), hardnesses at 2.5 mm, 5 mm, 7.5 mm, 10 mm, 12.5 mm and 15 mm points from a center of the spherical core toward a surface of the spherical core (Shore C hardness), and a surface hardness of the spherical core (Shore C hardness) are represented by H0, H2.5, H5, H7.4, H10, H12.5, H15 and Hs respectively, the following relation is satisfied: (H2.5?H0)>(H12.5?H10)>(Hs?H15).

Abstract: An object of the present disclosure is to provide a golf ball having excellent durability and flight distance and good shot feeling for an average golfer who hits a golf ball at a slow head speed. The present disclosure provides a golf ball comprising a spherical core and at least two cover layers covering the spherical core, wherein a difference between a core surface crosslinking density and a core center crosslinking density is more than 1.0×102 mol/m3 and less than 9.0×102 mol/m3, a hardness difference between a core surface hardness Cs (Shore C hardness) and a core center hardness Co (Shore C hardness) is 13.0 or more and 30.0 or less, a compression deformation amount of the core when applying a load from an initial load of 98 N to a final load of 1275 N to the core is 3.

Abstract: An outer surface of a tire can include a tread surface and a pair of side surfaces. A contour line of the tread surface can include a center arc, a pair of middle arcs, a pair of side arcs, and a pair of shoulder arcs. A contour line of each side surface can be connected to the shoulder arc. A position, on the outer surface, corresponding to a ground-contact end obtained by applying a load that is 80% of a standardized load, to the tire in a standardized state, and bringing the tire into contact with a flat surface is a reference ground-contact position, and a boundary between the shoulder arc and the side arc is a reference boundary. The reference boundary can be located axially outward of the reference ground-contact position. A ratio of a distance in an axial direction from an equator plane to the reference boundary to a distance in the axial direction from the equator plane to a tread reference end TE can be not less than 0.94 and not greater than 0.98.

Abstract: An object of the present disclosure is to provide a golf ball having excellent flight distance on driver shots and good spin rate on middle iron shots. The present disclosure provides a golf ball comprising a spherical core and a cover, wherein a hardness difference (C1-C0), a hardness difference (C2-C1), a hardness difference (C3-C2) and a hardness difference (C4-C3) are more than 0 and 6.0 or less, a hardness difference (C5-C4) is 5.0 or more, and a hardness difference (C6-C5), a hardness difference (C7-C6) and a hardness difference (C8-C7) are more than 0 and 3.5 or less where C0 (center), C1, C2, C3, C4, C5, C6, C7 and C8 (surface) are a Shore C hardness at each point from the center obtained by dividing a radius of the spherical core into equal eight parts.

Abstract: An object of the present invention is to provide a cured product of a golf ball rubber composition imparting excellent durability. The present invention provides a cured product of a golf ball rubber composition cured from a golf ball rubber composition containing (a) a base rubber, (b) an ?,?-unsaturated carboxylic acid having 3 to 8 carbon atoms and/or a metal salt thereof as a co-crosslinking agent, and (c) a crosslinking initiator, wherein the cured product of the golf ball rubber composition satisfies the following mathematical formula (1): Y<(0.1×X)?1.30??(1) in the formula (1), Y represents an effective crosslinking density of the cured product of the rubber composition (mmol/cc), and X represents an amount of the component (b) with respect to 100 parts by mass of (a) the base rubber (parts by mass).

Abstract: A tread portion includes a groove having first and second groove walls opposing each other, at least one first recess formed by partially recessing the first groove wall, and at least one second recess formed by partially recessing the second groove wall. A depth of each of the first and second recess from a ground contact surface is less than a groove depth of the groove. The first recess includes a first opening disposed at the first groove wall, and a first end portion extending substantially parallel to the first opening at a position farthest from the first opening. The second recess includes a second opening disposed at the second groove wall, and a second end portion extending substantially parallel to the second opening at a position farthest from the second opening. The first and second end portions are disposed so as not to oppose each other through the groove.

Abstract: A tire is provided with a shoulder circumferential groove, a crown circumferential groove, and middle lateral grooves. The middle lateral groove comprises: an axially outer part and an axially inner part which are inclined to the same direction as first inclined portions of the shoulder circumferential groove; and an in-between part which is inclined to the opposite direction to the axially outer part and the axially inner part. The axially outer part is smoothly continuous with the first inclined portion. The groove width WA1 at the axially outer end of the axially outer part is larger than the groove width WA2 at the axially inner end of the axially outer part, and the groove width WB1 at the axially outer end of the axially inner part is larger than the groove width WB2 at the axially inner end of the axially inner part.

Abstract: A tire comprising a tread part, wherein a ratio (G/WL) of a tire weight G (kg) with respect to a maximum load capability WL (kg) of the tire is 0.0131 or less, the tread comprises at least one rubber layer composed of a rubber composition comprising a rubber component and a reinforcing filler, tan ? at 30° C. (30° C. tan ?) of the rubber composition is over 0.15, and complex modulus at 30° C. (E*30) of the rubber composition is less than 8.0 MPa, and a ratio (30° C. tan ?/G) of the 30° C. tan ? with respect to the G is 0.016 or more.

Abstract: A golf club head includes a center of gravity spaced less than 5 mm from a vertical center plane that is perpendicular to a striking face plane and extends through a striking face center. The golf club head also includes a first component having a first melting point and a first density and a second component having a second melting point higher than the first melting point and a second density less than the first density. And the second component (i) is at least partially encapsulated by the first component, (ii) extends into a hosel portion below a hosel bore, and (iii) has a mass less than about 5 g.

Abstract: A tire comprises a tread portion comprising a shoulder land region provided with shoulder lateral grooves and circumferential sipes connecting between the shoulder lateral grooves. The shoulder lateral grooves are each provided with a chamfer. The circumferential sipes are each spaced apart from an axially inner end of the shoulder land region by an axial distance of from 30% to 100% of an axial width of the shoulder land region. The depths of the circumferential sipes are equal to or greater than the groove depths of the shoulder lateral grooves.

Abstract: An object of the present invention is to provide a diene-based polymer that can control the crosslinking morphology. The present invention provides a modified diene-based polymer having a structure represented by the formula (1). [In the formula (1), R1 and R2 represent an alkyl group having 1 or more carbon atoms, an aryl group having 6 or more carbon atoms, an aralkyl group having 6 or more carbon atoms, a hydrogen atom, or a halogen atom; and Z is an organic group, an organic group where a part of hydrogen atom of the above organic group is substituted, a hydrogen atom, or a halogen atom.

Abstract: A tyre includes a crown main groove formed by unit patterns. Each of the unit patterns includes a first inclined element, a second inclined element, a first bent element, and a second bent element. The first inclined element extends obliquely. The second inclined element extends obliquely in a direction opposite to the first inclined element. The first bent element extends so as to connect between the first inclined element and the second inclined element. The second bent element is connected with the second inclined element. The first bent element is bent so as to be convex toward the first tread edge without having a component extending in parallel with the tyre circumferential direction. The second bent element is bent so as to be convex toward the second tread edge without having the component extending in parallel with the tyre circumferential direction.

Abstract: Provided is a fitting apparatus configured to acquire measurement data obtained by measuring a swing action of a test club by a golfer, calculate one or more first indices representing an amount of change in an openness of a face surface of a head included in the test club at a time of the swing action based on the measurement data, calculate one or more second indices representing a characteristic of the swing action based on the measurement data, select a balance of a golf club suitable for the golfer, according to the one or more first indices, select at least one of a weight and a moment of inertia of a golf club suitable for the golfer, according to the one or more second indices, and select a golf club having the balance and the at least one of the weight and the moment of inertia.

Abstract: A manufacturing method includes the steps of: (A) preparing first and second sheet pieces 20a and 20b made of unvulcanized rubber; and (B) winding a long sheet 26 on a drum 6. The long sheet 26 includes the first and second sheet pieces 20a and 20b, and the second sheet piece 20b has a front edge joined to a rear edge of the first sheet piece 20a. Preferably, the step (B) includes the steps of: (B?1) joining the front edge of the second sheet piece 20b to the rear edge of the first sheet piece 20a to obtain the long sheet 26; and (B?2) feeding the sheet 26 from a servicer 4 to the drum 6 while rotating the drum 6 to wind the sheet 26 on the drum 6.

Abstract: An object of the present disclosure is to provide a cured product of a golf ball rubber composition imparting excellent durability to a golf ball. The present disclosure provides a cured product of a golf ball rubber composition containing (a) a base rubber, (b) an ?,?-unsaturated carboxylic acid having 3 to 8 carbon atoms and/or a metal salt thereof as a co-crosslinking agent, and (c) a crosslinking initiator, wherein an effective crosslinking density DC (mmol/cm3) of the cured product and a tensile modulus TM of the cured product at a strain (MPa) from 0.05% to 0.25% satisfy a relationship of TM?333.32×ln(DC)>100.

Abstract: A golf club head having a hollow portion therein, the head includes a main body including a crown portion and a sole portion, and a face member forming at least a part of a striking face for striking a ball. The main body is made of a first material having a first specific gravity. The face member is formed of a second material having a second specific gravity smaller than the first specific gravity. The main body is provided with at least one slit that penetrates the main body, and the at least one slit extends in a head-front-back direction.

Abstract: A tire comprising a tread, the tread comprising at least one rubber layer of a rubber composition comprising a rubber component, a filler, and a silane coupling agent, wherein a ratio (G/WL) of a tire weight G (kg) with respect to a maximum load capability WL (kg) of the tire is 0.0150 or less, and, where Wt (mm) is the tire cross-sectional width and Dt (mm) is the tire outer diameter, Wt and Dt satisfy the following Mathematical expression (1), and an average value of tan ? at 15° C. to 30° C. of the rubber composition, which average value is measured under conditions of a frequency of 10 Hz, an initial strain of 10%, and an amplitude of ±0.5%, is 0.