Patent Application
20100056302
1. Field of the Invention
The present invention relates to a golf ball and, more particularly, to a multilayer solid golf ball having an enclosing layer with a low thermal conductivity therein.
2. Description of the Related Art
The flying distance is an important index that we evaluate a golf ball. There are three main elements affecting the flying distance of the golf ball and they are “initial velocity”, “spin rate”, and “launch angle”. Initial velocity is one of the primary physical properties affecting the flying distance of the golf ball. The coefficient of restitution (COR) is an alternate parameter of initial velocity of the golf ball, and the temperature will affect the COR. Taking 24° C. as the standard temperature, the physical properties, including the COR, of the golf ball will be affected when the temperature is lower than 24° C. We find that the COR is significantly positive relative to the temperature, so the golf ball usually flies shorter in a cold weather.
When playing golf in a cold weather, 0° C. for example, a golfer may take one or more ways to warm the ball, including using body temperature or a golf ball heater, to raise the temperature of the golf ball so as to raise the COR of the golf ball that the golfer may drive the ball further. However, above warming ways cannot keep the raised temperature of the golf ball for a long time. Therefore, the raised COR of the golf ball cannot be kept for a long time by using above-mentioned ways. The temperature will drop quickly when the ball leaves the golfer's body or the golf ball heater, which will deteriorate the COR of the ball too. The sudden changes of the COR make it difficult for the golfer to predict and control the flying distance of the ball. Therefore, there is still a need to reduce the affection of the low temperature to the COR of the golf ball.
The primary objective of the present invention is to provide a multilayer solid golf ball, which has better properties in flying distance and ball control in a cold weather.
To achieve the objective of the present invention, a multilayer solid golf ball includes a core having a COR greater than 0.750, a cover surrounding the core, and an enclosing layer between the core and the cover. The enclosing layer has the thermal conductivity less than or equal to 0.20 W/m-K.
The present invention provides the enclosing layer with the low thermal conductivity between the core and the cover to improve the COR deterioration of the ball in a cold weather that may help the ball control and the flying distance.
As shown in
The core 10 has the COR greater than 0.750, more preferably greater than 0.770, and most preferably greater than 0.790. The core 10 may be made from a thermoplastic material or a thermosetting material, and the thermoplastic material is preferred. The thermoplastic material of the core 10 may be selected from the group consisting of ionomer resin, polyamide resin, polyester resin, polyurethane resin, and a mixture thereof. In the present embodiment, ionomer resin is preferred for the core 10. The suitable ionomer resin includes HPF and Surlyn®, both commercially available from E. I. Dupont de Nemous and Company, and IOTEK®, commercially available from Exxon Corporation. To get the greater COR, a main composition of the core 10 is preferably HPF, and Surlyn® and/or IOTEK® are sub-compositions which are optionally added therein. The sub-composition of the core 10 is in an amount of 0 to 10 parts by weight, based on 100 parts by weight of the main composition of the core 10. The core 10 may be made by hot-press molding or injection molding, and injection molding is preferred. The core 10 of the present invention may be single layer or multilayer construction, and except for the aforementioned materials, any other materials may be also used to make the core 10, as long as the core 10 has the COR greater than 0.750. A diameter of the core 10 may be in a range between 19.0 mm and 37.0 mm, a preferred diameter range is between 21.0 mm and 35.0 mm, and a more preferred diameter range is between 23.0 mm and 32.0 mm. The core 10 has an outer surface 11.
There is no specific limitation for the material of the cover 20. Any conventional material that is used to make the cover 20 may be used in the present invention.
The intermediate layer 30 has an inner surface 31 facing the enclosing layer 40 and an outer surface 32 facing the cover 20. The intermediate layer 30 may be made from a thermoplastic material or a thermosetting material. In the present invention, the thermosetting material is preferred, such as rubber composition. There are some base rubber that may be used in the rubber composition, such as 1,4-cis-polybutadiene, polyisoprene, styrene-butadiene copolymers, natural rubber, and a mixture thereof. To have a better resilient performance, 1,4-cis-polybutadiene is preferred. Alternatively, 1,4-cis-polybutadiene can be used as the base material for the intermediate layer 30 and mixed with other ingredients. However, the amount of 1,4-cis-polybutadiene should be at least 50 parts by weight, based on 100 parts by weight of the rubber composition.
Except for the base rubber of 1,4-cis-polybutadiene, other additives, such as a crosslinking agent and a filler with a greater specific gravity may be added to the rubber composition. The suitable crosslinking agent can be selected from the group consisting of zinc acrylate, magnesium acrylate, zinc methacrylate, and magnesium methacrylate. To get greater resilience, zinc acrylate is preferred. To increase a specific gravity, a suitable filler may be added in the rubber composition, such as zinc oxide, barium sulfate, calcium carbonate, and magnesium carbonate, and in the present invention, zinc oxide is preferred. In addition, a metal powder with a greater specific gravity may also be used as the filler, such as tungsten. By means of adjusting the added amount of the filler, the specific gravity of the intermediate layer 30 can reach the desired level. The thickness of the intermediate layer 30 is in a range between 2.0 mm and 11.0 mm, more preferably in a range of 2.1 mm and 9.5 mm, and most preferably in a range between 3.6 mm and 8.5 mm.
The enclosing layer 40 is between the core 10 and the intermediate layer 30. To keep the COR of the multilayer solid golf ball 100, the thickness of the intermediate layer 30 is less than or equal to 1 mm, more preferably in a range between 0.005 mm and 0.70 mm, and most preferably in a range between 0.01 mm and 0.4 mm. If the thickness of the enclosing layer 40 is less than 0.005 mm, the low thermal conductivity effect of the intermediate layer 40 is not significant. In the present embodiment, the enclosing layer 40 directly covers the outer surface 11 of the core 10. In other words, the enclosing layer 40 has an inner surface 41 contacting the outer surface 11 of the core 10 and an outer surface 42 contacting the inner surface 31 of the intermediate layer 30. The enclosing layer 40 is made from a material with a lower thermal conductivity. The thermal conductivity of the enclosing layer 40 is lower than that of the cover 20 or that of the intermediate layer 30. In the present embodiment, a value of the thermal conductivity of the enclosing layer 40 is less than or equal to 0.20 W/m-K so that the enclosing layer 40 will have a superior performance in reducing the conductivity of the cold from the cover 20 to the core 10. The thermal conductivity of the enclosing layer 40 is preferred between 0.04 W/m-K and 0.15 W/m-K, and is more preferred between 0.06 W/m-K and 0.15 W/m-K. In the present embodiment, the material of the enclosing layer 40 can be selected from the group consisting of ethylene vinyl acetate, polyurethane, polyester, polyamide, polyisoprene, polyvinyl chloride, acrylonitrile butadiene styrene, polyvinylidene fluoride, polyimide, and a mixture thereof. The material of the enclosing layer 40 is not limited to the above materials, any material having a thermal conductivity within the limitation of the present invention may be used.
As shown in table 1 to table 5, please compare with the Examples 1 and 3 and the Comparative Examples 1 and 3. The COR of the multilayer solid golf ball 100 of the present invention with the enclosing layer 40 will drop slower in a cold environment than the conventional multilayer golf ball without the enclosing layer, which proves that the multilayer solid golf ball 100 of the present invention has the higher COR in a cold environment to get a further flying distance and a better ball control.
There are still many ways to provide the enclosing layer 40.
The location of the enclosing layer is not limited in above preferred embodiments. As long as the enclosing layer is provided between the core and the cover, it may achieve the objective of the present invention.
In conclusion, the present invention provides a multilayer solid golf ball having an enclosing layer with lower thermal conductivity between the core and the cover of the multilayer solid golf ball that may reduce the conductivity of the cold from the cover to the core to make the golf ball still keep a sufficient COR in a cold environment.
Although a particular embodiment of the invention has been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.
