Castable polyurea compositions for golf ball covers

Abstract

Disclosed herein is a golf ball having improved cut and shear resistance. Such gold balls comprise a core, an inner cover layer, and an outer cover layer, the outer cover layer being formed from a polyurea or poly(urea-co-urethane) comprising: 1) a polyurea prepolymer comprising: the reaction product of at least one first polyisocyanate, wherein the polyisocyanate has a reactivity greater than that of 4,4′-methylene bis(cyclohexyl) isocyanate and a functionality of 1.7 to 2.3, and at least one amine-terminated compound, wherein the amine-terminated compound is selected from the group consisting of amine-terminated hydrocarbons, amine-terminated polyethers, amine-terminated polyesters, amine-terminated polycaprolactones, amine-terminated polycarbonates, amine-terminated polyamides, and mixtures thereof; and at least one second polyisocyanate with a vapor pressure lower than 0.01 mm Hg at 20° C.; and 2) at least one curing agent comprising amine or hydroxyl functional curatives.

Description

FIELD OF THE INVENTION[0001]This present invention is related to polyurea prepolymer compositions and to polyurea and poly(urea-co-urethane) elastomers produced therefrom. Such elastomers are useful in the manufacture of golf balls and golf ball covers.BACKGROUND[0002]Polyurethane elastomers and / or poly (urethane-co-urea) elastomers are widely used in the manufacture of golf balls and golf ball covers. See for example, U.S. Pat. Nos. 5,334,673, 7,244,384, 7,481,956 and 7,491,787. Polyurethanes allow for the production of the golf ball covers with the feel and click of balata covered balls and provide for greater cut resistance. In addition, the polyurethanes are generally more resilient than balata, allowing balls to be made with good feel and good distance. Another advantageous feature of polyurethane covered balls is shear resistance. Shear resistance measures the damage to a cover from the impact of a club with sharp grooves, which can tear away bit of the cover. In contrast, cut...

AI Technical Summary

Benefits of technology

[0035]The golf ball cover of this invention has good physical properties, such as good resilience, shear resistance, and heat stability equal to or exceed that of the more common polyurethanes and polyureas currently available for use. Surprisingly, the compositions of this invention have a desirable reactivity profile, such as long pot life, short demold time and no postcure at elevated temperatures. These characteristics make the invention suitable for both casting and reaction injection molding.

Problems solved by technology

Due to the fast reaction speed of amines and isocyantes, polyurea systems have only found commercial values in spray coatings and reaction injection moldings (RIM) instead of low pressure castings that is used in the production of high performance polyurethane elastomers.

Although polyurea compositions based on these isocyanates possess improved light stability, they are often accompanied by a decrease in the mechanical properties of the materials, which results in poor shear and cut resistance.

Extended postcure at elevated temperatures can significantly reduce productivity, and softening at elevated temperatures affects play range and spinning of the ball.

Due to the fast reaction between aromatic isocyanates and polyamines, aromatic polyisocyanates are not a prime candidate for polyurea prepolymer compositions, where vigorous reaction between polyamine and aromatic isocyanates can lead to a run away reaction and cause reactive chemical accidents.

As a result, they have generally been dismissed as potential candidates for polyurea prepolymers.

While an all polyurea system is desirable, some polyisocyanate based polyurea systems can be difficult to process via casting due to fast reactivity of the polyisocyanate.

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