GOLF BALL INCORPORATING CASING LAYER FOR CORE HAVING STEEP HARDNESS GRADIENT AND METHODS RELATING THERETO

1 . A golf ball comprising a core, a cover, and a casing layer disposed between the core and the cover;

wherein the core has a first outer surface and a geometric center;

the geometric center having a hardness X of from about 40 Shore C to about 75 Shore C and the first outer surface having a hardness Y of from about 75 Shore C to about 95 Shore C such that (15 Shore C)<(Y−X)≦(55 Shore C); and

wherein the casing layer is formed from a high acid divalent ionomeric composition and has an inner surface that is adjacent the first outer surface and a second outer surface surrounding the inner surface;

the second outer surface having a hardness Z of from about 90 Shore C to about 100 Shore C;

wherein (20 Shore C)<(Z−X)≦(60 Shore C); and

wherein the core has an Atti compression A of from about 40 to about 100, and wherein the core and the casing layer, combined, have an Atti compression B of from about 55 to about 115 such that 1.05≦(B/A)≦1.75; and

wherein the finished golf ball has an Atti compression of from about 60 to about 120.

2 . The golf ball of claim 1 , wherein the high acid divalent ionomeric composition is blended with a filler selected from the group consisting of fibers, flocks, flakes, glass flakes, microballoons, glass fibers, polymeric fiber, polymeric flock, silica and clay.

3 . The golf ball of claim 1 , wherein the high acid divalent ionomeric composition is partially neutralized with a divalent cation selected from the group consisting of zinc, magnesium, calcium, and blends thereof.

4 . The golf ball of claim 1 , wherein the high acid divalent ionomeric composition is an ethylene/methacrylic acid (E/MAA) copolymer having 19% methacrylic acid.

5 . The golf ball of claim 1 , wherein the cover has a cover inner surface adjacent the casing layer and a cover outer surface surrounding the cover inner surface, wherein the cover outer surface has a hardness Q of from about 70 Shore C to about 95 Shore C and wherein Q≦Z.

6 . The golf ball of claim 1 , wherein hardness X is from about 45 Shore C to about 70 Shore C, Y is from about 77 Shore C to about 86 Shore C and Z is from about 90 Shore C to about 94 Shore C.

7 . The golf ball of claim 5 , wherein hardness Q is from about 75 Shore C to about 94 Shore C.

8 . The golf ball of claim 1 , wherein hardness X is from about 55 Shore C to about 74 Shore C, Y is from about 81 Shore C to about 90 Shore C and Z is from about 93 Shore C to about 96 Shore C.

9 . The golf ball of claim 5 , wherein hardness Q is from about 80 Shore C to about 95 Shore C.

10 . The golf ball of claim 1 , wherein hardness X is from about 65 Shore C to about 68 Shore C, Y is from about 84 Shore C to about 89 Shore C and Z is from about 97 Shore C to about 99 Shore C.

11 . The golf ball of claim 5 , wherein hardness Q is from about 85 Shore C to about 95 Shore C.

12 . A golf ball comprising a core, a cover, and a casing layer disposed between the core and the cover;

wherein the core has a first outer surface and a geometric center;

the geometric center having a hardness X′ of from about 15 Shore D to about 54 Shore D and the first outer surface having a hardness Y′ of from about 35 Shore D to about 65 Shore D such that (10 Shore D)<(Y′−X′)≦(35 Shore D); and

wherein the casing layer is formed from a high acid divalent ionomeric composition and has an inner surface that is adjacent the first outer surface and a second outer surface surrounding the inner surface;

the second outer surface having a hardness Z′ of from about 60 Shore D to about 75 Shore D;

wherein (10 Shore D)<(Z′−X′)≦(55 Shore D); and

wherein the core has an Atti compression A of from about 40 to about 100, and wherein the core and the casing layer, combined, have an Atti compression B of from about 55 to about 115 such that 1.05≦(B/A)≦1.75; and

wherein the finished golf ball has an Atti compression of from about 60 to about 120.

13 . The golf ball of claim 12 , wherein the high acid divalent ionomeric composition is blended with a filler selected from the group consisting of fibers, flocks, flakes, glass flakes, microballoons, glass fibers, polymeric fiber, polymeric flock, silica, clay, and combinations thereof.

14 . The golf ball of claim 12 , wherein the high acid divalent ionomeric composition is neutralized with a divalent cation selected from the group consisting of zinc, magnesium, calcium, and blends thereof.

15 . The golf ball of claim 12 , wherein the high acid divalent ionomeric composition is an ethylene/methacrylic acid (E/MAA) copolymer having 19% methacrylic acid.

16 . The golf ball of claim 12 , wherein the cover has a cover inner surface adjacent the casing layer and a cover outer surface surrounding the cover inner surface, wherein the cover outer surface has a hardness Q′ of from about 50 shore D to about 68 Shore D and wherein Q′≦Z′.

17 . The golf ball of claim 16 , wherein hardness X′ is from about 20 Shore D to about 45 Shore D, Y′ is from about 35 Shore D to about 56 Shore D and Z′ is from about 62 Shore D to about 73 Shore D.

18 . The golf ball of claim 17 , wherein hardness Q′ is from about 50 Shore D to about 65 Shore D.

19 . The golf ball of claim 16 , wherein hardness X′ is from about 30 Shore D to about 40 Shore D, Y′ is from about 41 Shore D to about 54 Shore D and Z′ is from about 65 Shore D to about 71 Shore D.

20 . The golf ball of claim 19 , wherein hardness Q′ is from about 55 Shore D to about 65 Shore D.

21 . The golf ball of claim 12 , wherein hardness X′ is from about 35 Shore D to about 38 Shore D, Y′ is from about 48 Shore D to about 50 Shore D and Z′ is from about 68 Shore D to about 73 Shore D.

22 . The golf ball of claim 16 , wherein hardness Q′ is from about 60 Shore D to about 65 Shore D.

23 . A method of making a golf ball comprising:

providing a core;

wherein the core has a first outer surface and a geometric center; the geometric center having a hardness X of from about 40 Shore C to about 75 Shore C and the first outer surface having a hardness Y of from about 75 Shore C to about 95 Shore C such that (15 Shore C)<(Y−X)≦(55 Shore C); and

wherein the core has an Atti compression A of from about 40 to about 100;

forming a casing layer about the core;

wherein the casing layer is formed from a high acid divalent ionomeric composition and has an inner surface that is adjacent the first outer surface and a second outer surface surrounding the inner surface; the second outer surface having a hardness Z of from about 90 Shore C to about 100 Shore C;

wherein (20 Shore C)<(Z−X)≦(60 Shore C); and

wherein the core and the casing layer, combined, have an Atti compression B of from about 55 to about 115 such that 1.05≦(B/A)≦1.75; and

forming a cover about the casing layer such that the finished golf ball has an Atti compression of from about 60 to about 120.

24 . The method of claim 23 , wherein the high acid divalent ionomeric composition is blended with a filler selected from the group consisting of fibers, flocks, flakes, glass flakes, microballoons, glass fibers, polymeric fiber, polymeric flock, silica, clay, and combinations thereof.

25 . The method of claim 23 , wherein the high acid divalent ionomeric composition is neutralized with a divalent cation selected from the group consisting of zinc, magnesium and calcium.

26 . The golf ball of claim 23 , wherein the high acid divalent ionomeric composition is an ethylene/methacrylic acid (E/MAA) copolymer having 19% methacrylic acid.

27 . The method of claim 23 , wherein the cover has a cover inner surface adjacent the casing layer and a cover outer surface surrounding the cover inner surface, wherein the cover outer surface has a hardness Q of from about 70 Shore C to about 95 Shore C and wherein Q≦Z.

28 . The method of claim 23 , wherein hardness X is from about 45 Shore C to about 70 Shore C, Y is from about 77 Shore C to about 86 Shore C and Z is from about 90 Shore C to about 94 Shore C.

29 . The method of claim 27 , wherein hardness Q is from about 75 Shore C to about 94 Shore C.

30 . The method of claim 23 , wherein hardness X is from about 55 Shore C to about 74 Shore C, Y is from about 81 Shore C to about 90 Shore C and Z is from about 93 Shore C to about 96 Shore C.

31 . The method of claim 27 , wherein hardness Q is from about 80 Shore C to about 95 Shore C.

32 . The method of claim 23 , wherein hardness X is from about 65 Shore C to about 68 Shore C, Y is from about 84 Shore C to about 89 Shore C and Z is from about 97 Shore C to about 99 Shore C.

33 . The method of claim 27 , wherein hardness Q is from about 85 Shore C to about 95 Shore C.

34 . A method of making a golf ball comprising:

providing a core;

wherein the core has a first outer surface and a geometric center; the geometric center having a hardness X′ of from about 15 Shore D to about 54 Shore D and the first outer surface having a hardness Y′ of from about 35 Shore D to about 65 Shore D such that (10 Shore D)<(Y′−X′)≦(35 Shore D); and

wherein the core has an Atti compression A of from about 40 to about 100;

forming a casing layer about the core;

wherein the casing layer is formed from a high acid divalent ionomeric composition and has an inner surface that is adjacent the first outer surface and a second outer surface surrounding the inner surface; the second outer surface having a hardness Z′ of from about 60 Shore D to about 75 Shore D;

wherein (10 Shore D)<(Z′−X′)≦(55 Shore D); and

wherein the core and the casing layer, combined, have an Atti compression B of from about 55 to about 115; such that 1.05≦(B/A)≦1.75; and

forming a cover about the casing layer such that the finished golf ball has an Atti compression of from about 65 to about 120.

35 . The method of claim 34 , wherein the high acid divalent ionomeric composition is blended with a filler selected from the group consisting of fibers, flocks, flakes, glass flakes microballoons, glass fibers, polymeric fiber, polymeric flock, silica, clay, and combinations thereof.

36 . The method of claim 34 , wherein the high acid divalent ionomeric composition is neutralized with a divalent cation selected from the group consisting of zinc, magnesium, calcium, and blends thereof.

37 . The method of claim 34 , wherein the high acid divalent ionomeric composition is an ethylene/methacrylic acid (E/MAA) copolymer having 19% methacrylic acid.

38 . The method of claim 34 , wherein the cover has a cover inner surface adjacent the casing layer and a cover outer surface surrounding the cover inner surface, wherein the cover outer surface has a hardness Q′ of from about 50 shore D to about 68 Shore D and wherein Q≦Z.

39 . The method of claim 38 , wherein hardness X′ is from about 20 Shore D to about 45 Shore D, Y′ is from about 35 Shore D to about 56 Shore D and Z′ is from about 62 Shore D to about 73 Shore D.

40 . The method of claim 39 , wherein hardness Q′ is from about 50 Shore D to about 65 Shore D.

41 . The method of claim 38 , wherein hardness X′ is from about 30 Shore D to about 40 Shore D, Y′ is from about 43 Shore D to about 54 Shore D and Z′ is from about 65 Shore D to about 71 Shore D.

42 . The method of claim 41 , wherein hardness Q′ is from about 55 Shore D to about 65 Shore D.

43 . The method of claim 34 , wherein hardness X′ is from about 35 Shore D to about 38 Shore D, Y′ is from about 48 Shore D to about 50 Shore D and Z′ is from about 68 Shore D to about 73 Shore D.

44 . The method of claim 38 , wherein hardness Q′ is from about 60 Shore D to about 65 Shore D.