Multi-piece solid golf ball

1. A multi-piece solid golf ball comprising a core, an envelope layer encasing the core, an intermediate layer encasing the envelope layer, and a cover layer encasing the intermediate layer and having formed on an outer surface thereof a plurality of dimples,

wherein the core is formed primarily of a base rubber, the envelope layer and the intermediate layer are formed primarily of like or unlike synthetic resin materials, the cover layer is formed primarily of a urethane material, and conditions (1) to (4) below are satisfied:

(1) surface hardness (Shore D) of envelope layer-encased sphere<surface hardness (Shore D) of ball;

(2) cover layer thickness≤intermediate layer thickness;

(3) T−M>1.0 mm, where T (mm) is the deflection of the core when compressed under a final load of 1,275 N (130 kgf) from an initial load of 98 N (10 kgf) and M (mm) is the deflection of the ball when compressed under a final load of 1,275 N (130 kgf) from an initial load of 98 N (10 kgf); and

(4) initial velocity (m/s) of core>initial velocity (m/s) of ball; and

wherein the conditions below are satisfied:

(initial velocity of intermediate layer-encased sphere−initial velocity of envelope layer-encased sphere)>0 m/s; and

surface hardness (Shore D) of envelope layer-encased sphere<surface hardness (Shore D) of intermediate layer-encased sphere>surface hardness (Shore D) of ball.

2. The multi-piece solid golf ball of claim 1 which further satisfies conditions (5) to (7) below:

(5) (initial velocity of envelope layer-encased sphere−initial velocity of core)<0 m/s;

(6) [surface hardness (Shore D) of envelope layer-encased sphere−surface hardness (Shore D) of core]>0; and

(7) 0.25≤mm T−≤E 0.6 mm, where E (mm) is the deflection of the envelope layer-encased sphere when compressed under a final load of 1,275 N (130 kgf) from an initial load of 98 N (10 kgf).

3. The multi-piece solid golf ball of claim 1 which further satisfies conditions (10) and (11) below:

(10) −20≤[surface hardness (Shore D) of ball−surface hardness (Shore D) of intermediate layer-encased sphere]≤−1; and

(11) −2.5 m/s≤(initial velocity of ball−initial velocity of intermediate layer-encased sphere)≤+0.5 m/s.

4. The multi-piece solid golf ball of claim 1 which further satisfies conditions (12) and (13) below:

(12) −2 m/s≤(initial velocity of ball−initial velocity of envelope layer-encased sphere)≤+1 m/s; and

(13) −10≤[surface hardness (Shore D) of envelope layer-encased sphere−surface hardness (Shore D) of ball]≤+10.

5. A multi-piece solid golf ball comprising a core, an envelope layer encasing the core, an intermediate layer encasing the envelope layer, and a cover layer encasing the intermediate layer and having formed on an outer surface thereof a plurality of dimples,

wherein the core is formed primarily of a base rubber, the envelope layer and the intermediate layer are formed primarily of like or unlike synthetic resin materials, the cover layer is formed primarily of a urethane material, and conditions (1) to (4) below are satisfied:

(1) surface hardness (Shore D) of envelope layer-encased sphere<surface hardness (Shore D) of ball;

(2) cover layer thickness≤intermediate layer thickness;

(3) T−M>1.0 mm, where T (mm) is the deflection of the core when compressed under a final load of 1,275 N (130 kgf) from an initial load of 98 N (10 kgf) and M (mm) is the deflection of the ball when compressed under a final load of 1,275 N (130 kgf) from an initial load of 98 N (10 kgf); and

(4) initial velocity (m/s) of core>initial velocity (m/s) of ball; and

wherein the core is formed of a hot-molded product of a rubber composition comprising components (A) to (C) below:

(A) a base rubber;

(B) an organic peroxide; and

(C) water and/or a metal monocarboxylate; and

wherein the multi-piece solid golf ball further satisfies conditions (5) to (7) below:

(5) (initial velocity of envelope layer-encased sphere−initial velocity of core)<0 m/s;

(6) [surface hardness (Shore D) of envelope layer-encased sphere−surface hardness (Shore D) of core]>0; and

(7) 0.25≤mm T−≤E 0.6 mm, where E (mm) is the deflection of the envelope layer-encased sphere when compressed under a final load of 1275 N (130 kgf) from an initial load of 98 N (10 kgf).

6. The multi-piece solid golf ball of claim 1 , wherein the envelope layer is formed of a material obtained by blending as essential components:

100 parts by weight of a resin component composed of, in admixture,

a base resin of (a) an olefin-unsaturated carboxylic acid random copolymer and/or a metal ion neutralization product of an olefin-unsaturated carboxylic acid random copolymer mixed with (b) an olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ester random copolymer and/or a metal ion neutralization product of an olefin-unsaturated carboxylic acid-unsaturated carboxylic acid ester random copolymer in a weight ratio between 100:0 and 0:100, and

(e) a non-ionomeric thermoplastic elastomer

in a weight ratio between 100:0 and 50:50;

(c) from 5 to 80 parts by weight of a fatty acid and/or fatty acid derivative having a molecular weight of from 228 to 1500; and

(d) from 0.1 to 17 parts by weight of a basic inorganic metal compound capable of neutralizing un-neutralized acid groups in the base resin and component (c).

7. The multi-piece solid golf ball of claim 1 , wherein the intermediate layer is formed primarily of a resin mixture of a zinc-neutralized ionomer resin and a sodium-neutralized ionomer resin.

8. The multi-piece solid golf ball of claim 5 which further satisfies conditions (8) and (9) below:

(8) (initial velocity of intermediate layer-encased sphere−initial velocity of envelope layer-encased sphere)>0 m/s; and

(9) surface hardness (Shore D) of envelope layer-encased sphere<surface hardness (Shore D) of intermediate layer-encased sphere>surface hardness (Shore D) of ball.

9. The multi-piece solid golf ball of claim 5 which further satisfies conditions (10) and (11) below:

(10) −20≤[surface hardness (Shore D) of ball−surface hardness (Shore D) of intermediate layer-encased sphere]≤−1; and

(11) −2.5 m/s≤(initial velocity of ball−initial velocity of intermediate layer-encased sphere)≤+0.5 m/s.

10. The multi-piece solid golf ball of claim 5 which further satisfies conditions (12) and (13) below:

(12) −2 m/s≤(initial velocity of ball−initial velocity of envelope layer-encased sphere)≤+1 m/s; and

(13) −10≤[surface hardness (Shore D) of envelope layer-encased sphere−surface hardness (Shore D) of ball]≤+10.

11. A multi-piece solid golf ball comprising a core, an envelope layer encasing the core, an intermediate layer encasing the envelope layer, and a cover layer encasing the intermediate layer and having formed on an outer surface thereof a plurality of dimples,

wherein the core is formed primarily of a base rubber, the envelope layer and the intermediate layer are formed primarily of like or unlike synthetic resin materials, the cover layer is formed primarily of a urethane material, and conditions (1) to (4) below are satisfied:

(1) surface hardness (Shore D) of envelope layer-encased sphere<surface hardness (Shore D) of ball;

(2) cover layer thickness≤intermediate layer thickness;

(3) T−M>1.0 mm, where T (mm) is the deflection of the core when compressed under a final load of 1,275 N (130 kgf) from an initial load of 98 N (10 kgf) and M (mm) is the deflection of the ball when compressed under a final load of 1,275 N (130 kgf) from an initial load of 98 N (10 kgf); and

(4) initial velocity (m/s) of core>initial velocity (m/s) of ball; and

wherein the core is formed of a hot-molded product of a rubber composition comprising components (A) to (C) below:

(A) a base rubber;

(B) an organic peroxide; and

(C) water and/or a metal monocarboxylate; and

wherein the multi-piece solid golf ball further satisfies conditions (8) and (9) below:

(8) (initial velocity of intermediate layer-encased sphere−initial velocity of envelope layer-encased sphere)>0 m/s; and

(9) surface hardness (Shore D) of envelope layer-encased sphere<surface hardness (Shore D) of intermediate layer-encased sphere>surface hardness (Shore D) of ball.

12. The multi-piece solid golf ball of claim 11 which further satisfies conditions (10) and (11) below:

(10) −20≤[surface hardness (Shore D) of ball−surface hardness (Shore D) of intermediate layer-encased sphere]≤−1; and

(11) −2.5 m/s≤(initial velocity of ball−initial velocity of intermediate layer-encased sphere)≤+0.5 m/s.

13. The multi-piece solid golf ball of claim 11 which further satisfies conditions (12) and (13) below:

(12) −2 m/s≤(initial velocity of ball−initial velocity of envelope layer-encased sphere)≤+1 m/s; and

(13) −10≤[surface hardness (Shore D) of envelope layer-encased sphere−surface hardness (Shore D) of ball]≤+10.

14. A multi-piece solid golf ball comprising a core, an envelope layer encasing the core, an intermediate layer encasing the envelope layer, and a cover layer encasing the intermediate layer and having formed on an outer surface thereof a plurality of dimples,

wherein the core is formed primarily of a base rubber, the envelope layer and the intermediate layer are formed primarily of like or unlike synthetic resin materials, the cover layer is formed primarily of a urethane material, and conditions (1) to (4) below are satisfied:

(1) surface hardness (Shore D) of envelope layer-encased sphere<surface hardness (Shore D) of ball;

(2) cover layer thickness≤intermediate layer thickness;

(3) T−M>1.0 mm, where T (mm) is the deflection of the core when compressed under a final load of 1,275 N (130 kgf) from an initial load of 98 N (10 kgf) and M (mm) is the deflection of the ball when compressed under a final load of 1,275 N (130 kgf) from an initial load of 98 N (10 kgf); and

(4) initial velocity (m/s) of core>initial velocity (m/s) of ball; and

wherein the core is formed of a hot-molded product of a rubber composition comprising components (A) to (C) below:

(A) a base rubber;

(B) an organic peroxide; and

(C) water and/or a metal monocarboxylate; and

wherein the multi-piece solid golf ball further satisfies conditions (10) and (11) below:

(10) −20≤[surface hardness (Shore D) of ball−surface hardness (Shore D) of intermediate layer-encased sphere]≤−1; and

(11) −2.5 m/s≤(initial velocity of ball−initial velocity of intermediate layer-encased sphere)≤+0.5 m/s.

15. The multi-piece solid golf ball of claim 14 which further satisfies conditions (12) and (13) below:

(12) −2 m/s≤(initial velocity of ball−initial velocity of envelope layer-encased sphere)≤+1 m/s; and

(13) −10≤[surface hardness (Shore D) of envelope layer-encased sphere−surface hardness (Shore D) of ball]≤+10.

16. A multi-piece solid golf ball comprising a core, an envelope layer encasing the core, an intermediate layer encasing the envelope layer, and a cover layer encasing the intermediate layer and having formed on an outer surface thereof a plurality of dimples,

wherein the core is formed primarily of a base rubber, the envelope layer and the intermediate layer are formed primarily of like or unlike synthetic resin materials, the cover layer is formed primarily of a urethane material, and conditions (1) to (4) below are satisfied:

(1) surface hardness (Shore D) of envelope layer-encased sphere<surface hardness (Shore D) of ball;

(2) cover layer thickness≤intermediate layer thickness;

(3) T−M>1.0 mm, where T (mm) is the deflection of the core when compressed under a final load of 1,275 N (130 kgf) from an initial load of 98 N (10 kgf) and M (mm) is the deflection of the ball when compressed under a final load of 1,275 N (130 kgf) from an initial load of 98 N (10 kgf); and

(4) initial velocity (m/s) of core>initial velocity (m/s) of ball; and

wherein the core is formed of a hot-molded product of a rubber composition comprising components (A) to (C) below:

(A) a base rubber;

(B) an organic peroxide; and

(C) water and/or a metal monocarboxylate; and

wherein the multi-piece solid golf ball further satisfies conditions (12) and (13) below:

(12) −2 m/s≤(initial velocity of ball−initial velocity of envelope layer-encased sphere)≤+1 m/s; and

(13) −10≤[surface hardness (Shore D) of envelope layer-encased sphere−surface hardness (Shore D) of ball]≤+10.