An object of the present invention is to provide a resin composition for the golf ball that suppresses the bleed out of the low molecular weight material component, as well as improves the fluidity and repulsion performance. The present invention provides a golf ball forming resin composition comprising as a resin component, (A) a high melt viscosity resin; (B) a low melt viscosity ionomer resin having a melt viscosity (190° C.) ranging from 1 Pa·s to 10 Pa·s measured by a brookfield viscometer, in a ratio of (A) the high melt viscosity resin/(B) the low melt viscosity ionomer resin being 55 mass % to 99 mass %/45 mass % to 1 mass %; and (C) a metal ion source capable of neutralizing carboxyl groups of (A) the high melt viscosity resin and (B) the low melt viscosity ionomer resin, in an amount of from 0.1 part to 10 parts with respect to 100 parts by mass of a sum of (A) the high melt viscosity resin and (B) the low melt viscosity ionomer resin.
1. A golf ball comprising:
a core consisting of a center and at least one intermediate layer covering the center,
a cover covering the core, wherein at least one piece or one layer of the intermediate layer is formed from a golf ball forming resin composition comprising as a resin component,
(A) a high melt viscosity resin containing:
(a-1) a high melt viscosity ionomer resin having a melt viscosity (190° C.) ranging from 500 Pa·s to 100,000 Pa·s measured by a flow tester and consisting of a metal ion-neutralized product of a binary copolymer composed of ethylene and α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms, a metal ion-neutralized product of a ternary copolymer composed of ethylene, α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and α,β-unsaturated carboxylic acid ester, or a mixture thereof, and/or
(a-2) a high melt viscosity nonionic resin having a melt viscosity (190° C.) ranging from 5 Pa·s to 3,000 Pa·s measured by a flow tester and consisting of a binary copolymer composed of ethylene and α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms, a ternary copolymer composed of ethylene, α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and α,β-unsaturated carboxylic acid ester, or a mixture thereof;
(B) a low melt viscosity ionomer resin having a melt viscosity (190° C.) ranging from 1 Pa·s to 10 Pa·s measured by a brookfield viscometer, and consisting of a metal ion-neutralized product of a binary copolymer composed of ethylene and α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms, a metal ion-neutralized product of a ternary copolymer composed of ethylene, α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and α,β-unsaturated carboxylic acid ester, or a mixture thereof, in a ratio of (A) the high melt viscosity resin/(B) the low melt viscosity ionomer resin being 55 mass % to 99 mass %/45 mass % to 1 mass %; and
(C) a metal ion source capable of neutralizing carboxyl groups of (A) the high melt viscosity resin and (B) the low melt viscosity ionomer resin, in an amount of from 0.1 part to 10 parts with respect to 100 parts by mass of a sum of (A) the high melt viscosity resin and (B) the low melt viscosity ionomer resin;
wherein the golf ball forming resin composition has a melt flow rate (190° C., 2.16 kg) ranging from 10 g/10 min to 100 g/10 min.
2. The golf ball according to claim 1 , wherein (A) the high melt viscosity resin consists of (a-1) the high melt viscosity ionomer resin as a resin component.
3. The golf ball according to claim 1 , wherein (A) the high melt viscosity resin consists of (a-2) the high melt viscosity nonionic resin as a resin component.
4. The golf ball according to claim 1 , wherein (A) the high melt viscosity resin contains (a-1) the high melt viscosity ionomer resin and (a-2) the high melt viscosity nonionic resin in a ratio of (a-1) the high melt viscosity ionomer resin to (a-2) the high melt viscosity nonionic resin being 1 mass % to 90 mass % to 99 mass % to 10 mass %.
5. The golf ball according to claim 1 , wherein the golf ball forming resin composition further comprises (D) a thermoplastic resin and/or thermosetting resin in an amount from 0 part (exclusive) to 100 parts with respect to 100 parts by mass of a sum of (A) the high melt viscosity resin and (B) the low melt viscosity ionomer resin.
6. The golf ball according to claim 1 , wherein the golf ball forming resin composition has a slab hardness ranging from 20 to 70 in Shore D hardness.
7. The golf ball according to claim 1 , wherein the intermediate layer has a thickness ranging from 0.1 mm to 2.0 mm.
8. A method for producing a golf ball having a core consisting of a center and at least one intermediate layer covering the center and a cover covering the core, comprising:
mixing (A) a high melt viscosity resin containing (a-1) a high melt viscosity ionomer resin having a melt viscosity (190° C.) ranging from 500 Pa·s to 100,000 Pa·s measured by a flow tester and consisting of a metal-ion neutralized product of a binary copolymer composed of ethylene and α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms, a metal ion neutralized product of a ternary copolymer composed of ethylene, α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and α,β-unsaturated carboxylic acid ester, or a mixture thereof, and/or (a-2) a high melt viscosity nonionic resin having a melt viscosity (190° C.) ranging from 5 Pa·s to 3,000 Pa·s measured by a flow tester and consisting of a binary copolymer composed of ethylene and α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms, a ternary copolymer composed of ethylene, α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and α,β-unsaturated carboxylic acid ester, or a mixture thereof;
(B) a low melt viscosity ionomer resin having a melt viscosity (190° C.) ranging from 1 Pa·s to 10 Pa·s measured by a brookfield viscometer, and consisting of a metal ion-neutralized product of a binary copolymer composed of ethylene and α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms, a metal-ion-neutralized product of a ternary copolymer composed of ethylene, α,β-unsaturated carboxylic acid having 3 to 8 carbon atoms and α,β-unsaturated carboxylic acid ester, or a mixture thereof, and
(C) a metal ion source capable of neutralizing carboxyl groups of (A) the high melt viscosity resin and (B) the low melt viscosity ionomer resin, in a ratio of (A) the high melt viscosity resin/(B) the low melt viscosity ionomer resin being 55 mass % to 99 mass %/45 mass % to 1 mass %; and in an amount of (C) the metal ion source being from 0.1 part to 10 parts with respect to 100 parts by mass of a sum of (A) the high melt viscosity resin and (B) the low melt viscosity ionomer resin, thereby neutralizing carboxyl groups of (A) the high melt viscosity resin and (B) the low melt viscosity ionomer resin and preparing a golf ball forming resin composition having a melt flow rate (190° C., 2.16 kg) ranging from 10 g/10 min to 100 g/10 min;
molding an intermediate layer from the golf ball forming resin composition; and
forming a cover from a cover composition onto the intermediate layer.