Urethane elastomers with improved color stability

Abstract

A golf ball including a center, a cover, and, optionally, at least one intermediate layer disposed between the center and the cover, wherein the cover is formed from a polyurethane composition, or a reaction product thereof, including at least one polyol; at least one polyisocyanate; at least one curing agent; and at least one color stabilizer; wherein the color stabilizer is present in an amount sufficient to provide a ΔC* of less than about 22 upon exposure to UV light over a timeframe of 1 hour.

What is claimed is:  
     
         1 . A golf ball comprising a center, a cover, and, optionally, at least one intermediate layer disposed between the center and the cover, wherein the cover is formed from a polyurethane composition, or a reaction product thereof, comprising: 
 at least one polyol;    at least one polyisocyanate;    at least one curing agent; and    at least one color stabilizer;    wherein the color stabilizer is present in an amount sufficient to provide a ΔC* of less than about 22 upon exposure to UV light over a timeframe of 1 hour.    
     
     
         2 . The golf ball of  claim 1 , wherein the cover has at least one of a material hardness of less than about 80 Shore D, a flexural modulus of less than about 100,000 psi, a dimple coverage of greater than about 60% and an ATTI compression of less than about 120.  
     
     
         3 . The golf ball of  claim 1 , wherein the cover has at least one of a material hardness of less than about 70 Shore D, a flexural modulus of less than about 75,000 psi, a dimple coverage of greater than about 65% and an ATTI compression of less than about 100.  
     
     
         4 . The golf ball of  claim 1 , wherein the cover has at least one of a material hardness of less than about 60 Shore D, a flexural modulus of less than about 60,000 psi, a dimple coverage of greater than about 70% and an ATTI compression of less than about 90.  
     
     
         5 . The golf ball of  claim 1 , wherein the color stabilizer comprises UV absorbers, radical scavengers, hindered amine light stabilizers, thermal stabilizers, antioxidants, quenchers, hydroperoxide decomposers, fillers, and combinations thereof.  
     
     
         6 . The golf ball of  claim 5 , wherein the color stabilizer comprises a UV absorber, a light stabilizer, or a combination thereof.  
     
     
         7 . The golf ball of  claim 6 , wherein the UV absorber comprises triazines, benzoxazinones, benzotriazoles, benzophenones, benzoates, formamidines, cinnamates/propenoates, aromatic propanediones, benzimidazoles, cycloaliphatic ketones, formanilides, cyanoacrylates, benzopyranones, and mixtures thereof.  
     
     
         8 . The golf ball of  claim 6 , wherein the UV absorber is present in an amount between about 0.1 weight percent and about 6.0 weight percent.  
     
     
         9 . The golf ball of  claim 8 , wherein the UV absorber is present in an amount between about 1.0 weight % to about 5.0 weight %.  
     
     
         10 . The golf ball of  claim 9 , wherein the UV absorber is present in an amount between about 3.0 weight % and about 5.0 weight %.  
     
     
         11 . The golf ball of  claim 6 , wherein the light stabilizer comprises bis-(substituted) heteropolycyclicdione; N,N′-1,6-hexanediylbis {N-(2,2,6,6-tetramethyl-4-piperidinyl)-formamide}; dimethyl succinate polymer with 4-hydroxy-2,2,6,6-tetra-methyl-1-piperidine ethanol; bis-(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate; hindered amine; 3-dodecyl-1-(2,2,6,6-tetramethyl-4-piperidyl-pyrrolidin-2,5-dione; poly-methylpropyl-3-oxy-[4(2,2,6,6-tetramethyl) piperidinyl] siloxane; bis-(1,2,2,6,6-pentamethyl-4-piperidinyl)-sebacate; bis-(2,2,6,6-tetramethyl-4-piperidinyl)-sebacate; bis-(1-octyloxy-2,2,6,6,tetramethyl-4-piperidinyl) sebacate; n-butyl-(3,5-di-t-butyl-4-hydroxybenzyl) bis-(1,2,2,6-pentamethyl-4-piperidinyl) malonate; bis-(2,2,6,6-tetramethyl-4-piperidinyl) sebacate; compounds containing at least one of the following structure:  
       
         
           
           
               
               
           
         
       
       and mixtures thereof.  
     
     
         12 . The golf ball of  claim 11 , wherein the light stabilizer is present in an amount between about 0.01 weight % and about 3 weight %.  
     
     
         13 . The golf ball of  claim 12 , wherein the light stabilizer is present in an amount between about 0.05 weight % and about 2 weight %.  
     
     
         14 . The golf ball of  claim 13 , wherein the light stabilizer is present in an amount between about 0.1 weight % and about 1.0 weight %.  
     
     
         15 . The golf ball of  claim 1 , wherein the polyisocyanate comprises 4,4′-diphenylmethane diisocyanate; polymeric 4,4′-diphenylmethane diisocyanate; carbodiimide-modified liquid 4,4′-diphenylmethane diisocyanate; 4,4′-dicyclohexylmethane diisocyanate; p-phenylene diisocyanate; toluene diisocyanate; 3,3′-dimethyl-4,4′-biphenylene diisocyanate; isophoronediisocyanate; hexamethylene diisocyanate; naphthalene diisocyanate; xylene diisocyanate; p-tetramethylxylene diisocyanate; m-tetramethylxylene diisocyanate; ethylene diisocyanate; propylene-1,2-diisocyanate; tetramethylene-1,4-diisocyanate; cyclohexyl diisocyanate; 1,6-hexamethylene-diisocyanate; dodecane-1,12-diisocyanate; cyclobutane-1,3-diisocyanate; cyclohexane-1,3-diisocyanate; cyclohexane-1,4-diisocyanate; 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane; methyl cyclohexylene diisocyanate; isocyanurate of methyl cyclohexylene diisocyanate; isocyanurate of 2,4,4-trimethyl-1,6-hexane diisocyanate; tetracene diisocyanate; napthalene diisocyanate; anthracene diisocyanate; and mixtures thereof.  
     
     
         16 . The golf ball of  claim 1 , wherein the curing agent comprises a polyamine or a polyol.  
     
     
         17 . The golf ball of  claim 1 , wherein the curing agent comprises at least one aromatic polyamine.  
     
     
         18 . The golf ball of  claim 1 , wherein the polyurethane composition has an initial C* value of less than about 5 and an L* value of greater than about 87.  
     
     
         19 . The golf ball of  claim 18 , wherein the polyurethane composition has an initial C* value of less than about 4 and an L* value of greater than about 87.  
     
     
         20 . The golf ball of  claim 1 , wherein the polyurethane composition has a C* value of less than about 20 and an L* value of greater than about 86 after exposure to UV light for 1 hour.  
     
     
         21 . The golf ball of  claim 20 , wherein the polyurethane composition has a C* value of less than about 15 and an L* value of greater than about 86 after exposure to UV light for 1 hour.  
     
     
         22 . The golf ball of  claim 1 , wherein the polyurethane composition has a C* value of less than about 25 and an L* value of greater than about 85 after exposure to UV light for 2 hours.  
     
     
         23 . The golf ball of  claim 22 , wherein the polyurethane composition has a C* value of less than about 20 and an L* value of greater than about 85 after exposure to UV light for 2 hours.  
     
     
         24 . The golf ball of  claim 1 , wherein the polyurethane composition has a C* value of less than about 25 and an L* value of greater than about 83 after exposure to UV light for 4 hours.  
     
     
         25 . The golf ball of  claim 24 , wherein the polyurethane composition has a C* value of less than about 23 and an L* value of greater than about 83 after exposure to UV light for 4 hours.  
     
     
         26 . The golf ball of  claim 1 , wherein the polyurethane composition has a ΔL* value of greater than about −4 and an ΔC* value of less than about 22.0 after exposure to UV light for about 1 hour.  
     
     
         27 . The golf ball of  claim 26 , wherein ΔC* is less than about 15.  
     
     
         28 . The golf ball of  claim 27 , wherein ΔC* is less than about 12.  
     
     
         29 . The golf ball of  claim 1 , wherein the polyurethane composition has a ΔL* value of greater than about −4 and an ΔC* value of less than about 22 after exposure to UV light for about 2 hours.  
     
     
         30 . The golf ball of  claim 29 , wherein ΔC* is less than about 15.  
     
     
         31 . The golf ball of  claim 30 , wherein ΔC* is less than about 13.  
     
     
         32 . The golf ball of  claim 1 , wherein the polyurethane composition has a ΔL* value of greater than about −7 and an ΔC* value of less than about 26 after exposure to UV light for about 4 hours.  
     
     
         33 . The golf ball of  claim 32 , wherein ΔC* is less than about 18.  
     
     
         34 . The golf ball of  claim 1 , wherein the cover comprises at least an inner cover layer and an outer cover layer comprising the polyurethane composition that is disposed about the inner cover layer.  
     
     
         35 . The golf ball of  claim 1 , wherein the cover is at least about 0.02 inches thick, the cover has a material hardness of less than about 80 Shore D, or both.  
     
     
         36 . The golf ball of  claim 1 , wherein a paint layer that is substantially free of UV absorber and light stabilizer is disposed about the cover.  
     
     
         37 . The golf ball of  claim 1 , wherein the at least one UV absorber and the at least one light stabilizer have a ratio of about 1:1 to about 100:1.  
     
     
         38 . The golf ball of  claim 37 , wherein the at least one UV absorber and the at least one light stabilizer have a ratio of about 7:1 to about 70:1.  
     
     
         39 . The golf ball of  claim 38 , wherein the at least one UV absorber and the at least one light stabilizer have a ratio of about 30:1 to about 50:1.  
     
     
         40 . The golf ball of  claim 1 , wherein the polyisocyanate comprises m-phenylene diisocyanate.  
     
     
         41 . The golf ball of  claim 6 , wherein the UV absorber is present in an amount between about 0.1 weight percent and about 10.0 weight percent.  
     
     
         42 . The golf ball of  claim 41 , wherein the UV absorber is present in an amount between about 1.0 weight % to about 7.0 weight %.  
     
     
         43 . The golf ball of  claim 42 , wherein the UV absorber is present in an amount between about 3.0 weight % and about 7.0 weight %.  
     
     
         44 . A golf ball comprising a center, a cover, and at least one intermediate layer disposed between the center and the cover, wherein the cover is formed from a polyurethane composition, or a reaction product thereof, comprising at least one UV absorber and at least one light stabilizer present in an amount sufficient to provide a ΔC* of less than about 22 upon exposure to UV light over a timeframe of 1 hour.  
     
     
         45 . A golf ball comprising a center, a cover, and at least one intermediate layer disposed between the center and the cover, wherein the cover is formed from a polyurethane composition, or a reaction product thereof, comprising: 
 a prepolymer comprising at least one diisocyanate and at least one polyol;    a curing agent;    at least one UV absorber; and    at least one light stabilizer;    wherein the at least one UV absorber and light stabilizer are present in an amount sufficient to provide a ΔC* of less than about 22 upon exposure to UV light over a timeframe of 1 hour.    
     
     
         46 . The golf ball of  claim 43 , wherein the polyisocyanate comprises 4,4′-diphenylmethane diisocyanate; polymeric 4,4′-diphenylmethane diisocyanate; carbodiimide-modified liquid 4,4′-diphenylmethane diisocyanate; 4,4′-dicyclohexylmethane diisocyanate; p-phenylene diisocyanate; toluene diisocyanate; 3,3′-dimethyl-4,4′-biphenylene diisocyanate; isophoronediisocyanate; hexamethylene diisocyanate; naphthalene diisocyanate; xylene diisocyanate; p-tetramethylxylene diisocyanate; m-tetramethylxylene diisocyanate; ethylene diisocyanate; propylene-1,2-diisocyanate; tetramethylene-1,4-diisocyanate; cyclohexyl diisocyanate; 1,6-hexamethylene-diisocyanate; dodecane-1,1 2-diisocyanate; cyclobutane-1,3-diisocyanate; cyclohexane-1,3-diisocyanate; cyclohexane-1,4-diisocyanate; 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane; m-phenylene diisocyanate; methyl cyclohexylene diisocyanate; isocyanurate of methyl cyclohexylene diisocyanate; isocyanurate of 2,4,4-trimethyl-1,6-hexane diisocyanate; tetracene diisocyanate; napthalene diisocyanate; anthracene diisocyanate; and mixtures thereof.  
     
     
         47 . A golf equipment-forming composition comprising: 
 a reaction product of a prepolymer comprising at least one diisocyanate and at least one polyol;    a curing agent comprising at least one polyamine;    at least one UV absorber; and    at least one light stabilizer;    wherein the at least one UV absorber and light stabilizer are present in an amount sufficient to provide a ΔC* of less than about 22 upon exposure to UV light over a timeframe of 1 hour.    
     
     
         48 . A method of inhibiting or preventing color degradation in a golf ball which comprises: 
 providing a golf ball core;    forming a cover about the core, wherein the cover is formed of a polyurethane composition, or a reaction product thereof, comprising at least one polyol, at least one polyisocyanate, at least one curing agent, and a color stabilizer present in an amount sufficient to provide a ΔC* of less than about 22 upon exposure to UV light over a timeframe of 1 hour.    
     
     
         49 . A method of testing the color stability of a golf ball which comprises: 
 providing a golf ball having an outermost cover formed of a stabilized polyurethane composition;    exposing the outermost cover to UV light for at least one hour; and    determining the C* value and L* value of the outermost cover.