JPS62176465A - Golf ball for floating exercise - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a floating practice golf ball.

[Conventional technology]

In general, the performance required for a practice golf ball is, first of all, to have a feel that is similar to a round ball and a trajectory shape similar to a round ball, and a practice golf ball must have these characteristics. It is believed that by providing the golf ball, the skills of golfers who practice with the practice ball will improve.

In other words, by being able to reproduce the trajectory during golf play on the driving range, it becomes easier to improve inconvenient areas such as swing and address. It is thought that a nice shot does not necessarily lead to a nice shot in golf play.

By the way, practice golf balls can be broadly classified into two types depending on the location conditions of the practice range. One is the so-called normal range ball, which is usually hit into an area called a golf range surrounded by a net (not necessarily surrounded in foreign countries), and the other is,
This is a water golf ball that is hit into ponds, lakes, etc. In water golf, which is adopted due to geographical or economic factors, it is essential that the balls used float on the water in order to facilitate recovery, so they are called floating balls. It is.

On the other hand, there are established standards for round golf balls, and the weight and outer diameter of the ball are regulated. In other words, the outer diameter of the ball is 1.6 for a large size ball.
80 inches (42.67m) or more, ball weight 1.
It weighs less than 62 ounces (45.92 g). A golfer's dream is to extend the distance even by 1 meter, and for this reason, the outer diameter of the ball is usually designed to be at the lower limit, and the weight of the ball to be at the upper limit, in order to gain even the slightest advantage in terms of distance. ing. As a result, the specific gravity of a round golf ball is approximately 1.
1 to 1.2, and small size balls have even higher specific gravity, and regular round balls do not float on water.

In comparison, in the case of a floating ball, the specific gravity is 1.
Since it needs to be 0 or less, even if the specific gravity is 0.99, which is just above the upper limit, the weight of a large size ball is 3.
It weighs 9 to 40 g, which is 5 to 6 g compared to a round ball.
It's lighter.

Incidentally, golf balls are provided with dimples to increase flight distance, and this increases the flight distance by approximately 100 meters compared to a ball with a smooth floor. The role of this dimple is generally to promote turbulent flow transition in the boundary layer and cause turbulent separation, which causes the separation point to move backward and the separation area to be smaller than the laminar flow separation when no dimples are provided. The pressure resistance can be reduced by
There are two points: improving lift by increasing the difference between the upper and lower separation points.

However, with a floating ball, the downward force of gravity is only 39-40g even in the case of a large size ball, and the same lifting force as a round ball is exerted (I).
In the case of IIJ, the trajectory of the floating ball will be more upward than that of the round ball, and if hit under the same conditions, the floating ball will have a clearly different trajectory than the round ball. In spite of this, in the prior art, the unique physical properties of floating balls have not been deeply explored, and floating balls have only been provided with dimples similar to those of ordinary round balls.

[Problem that the invention seeks to solve]

As mentioned above, conventional floating balls have dimples similar to those of regular round balls, so their trajectory is different from that of round balls, and when hit under the same conditions, the trajectory of a round ball is cannot be reproduced with a floating ball, and as a result, there is a problem in that the techniques learned using a floating ball are not necessarily useful when using a round ball.

[Means for solving problems]

The present invention aims to improve the trajectory of a floating ball by incorporating dimples that reduce lift into the floating ball, thereby bringing the trajectory of the floating ball closer to that of a round ball.

That is, the present invention provides a floating ball with a specific gravity of 1 or less, a diameter of 3.5 to 4, a diameter of 0LIII, and a total volume of 40.
Dimples of 0 to 600+no+3 are provided.

Specifically, when golf balls have the same weight and diameter, dimples are considered to be a major factor that influences the lift and resistance of the golf ball.

Incidentally, in the case of first-class round balls, considerable research has recently been conducted on the influence of dimples on the trajectory of the ball, and appropriate dimples have been proposed. However, it is no exaggeration to say that no research has been done on dimples in range balls, including floating balls, and as mentioned above, the dimples used in round balls are used as they are in floating balls. This is the reality.

Therefore, in the present invention, as a means of reducing lift without significantly changing the drag force, we devised a method of increasing the total volume of the dimples than the range that has been adopted for round balls, and through experiments, we found that a good flight trajectory shape was achieved. I found out what I could get.

In other words, the total volume of dimples used in round balls is 200 to 370 IIl11 according to actual measurements.
13 theal, but in the present invention this is 400-600+nm
By increasing the number to 3, it was possible to control lift without causing large changes in drag. In addition, floating balls have the disadvantage that their trajectory fluctuates between the highest point of the trajectory and landing on the water due to their light weight. Greater than 3.41, 3.5-4. Omn reduces the critical Reynolds number and keeps the drag coefficient low in the low-speed region from the highest point of the trajectory to landing on the water, thereby preventing the above-mentioned wobbling and creating a round ball that is light but has elasticity. It was possible to obtain a trajectory similar to that of a bullet.

In the present invention, the total volume of the dimples is set to 400 to 600au+3 as mentioned above, but this is because if the total volume of the dimples is less than 400+aI113, the effect of reducing the lift of the ball will not be sufficiently exerted, resulting in a high trajectory. The trajectory will be different from that of a round ball, and if the total dimple volume exceeds 60011II13, the lift will be extremely reduced, and the increase in drag cannot be ignored, resulting in a low trajectory that almost drops, resulting in a round ball. This is because the trajectory will be different from the trajectory of the ball, and the loss in flight distance will be large.

From the above point of view, the total dimple volume is 400
A narrower range within the range of ~600+n+3 is desirable, and a range of 450-520+nm3 is particularly preferred. In addition, in the present invention, the dimple diameter is set to 3.5 to 4.0 mm, but if the dimple diameter is smaller than 3.51 mm, it is not possible to sufficiently eliminate trajectory fluctuation; This is because if the diameter of the dimples is larger than 4.0 mm, adjacent dimples will overlap and the dimples will not be able to exhibit their full effect.

As mentioned above, the total dimple volume is 400 to 600 II.
II3, by setting the dimple diameter to 3.5 to 4.0 LII11, it is possible to reduce the lift force and prevent the ball from wobbling from the highest point to landing on the water.
Such an effect is exhibited regardless of the total number of dimples. For example, a floating golf ball pull typically has 250-450 pieces, especially 300-40 pieces.
However, the above effect applies not only when the total number of dimples is within the above range of 250 to 450, but also when the total number of dimples slightly deviates from the above range due to brand printing or manufacturing reasons. It will be performed in the same way no matter what.

In addition, the total dimple volume is 400-600III113
Setting the dimple diameter to 3.5 to 4.0 ma+ can be used for both one-piece golf balls and multilayer golf balls, and good results can be obtained. There are no particular limitations as long as it can be used for floating balls, and of course conventionally used ones can also be used, but in particular one-piece balls obtained by crosslinking the following rubber compositions or the following rubbers: A golf ball with a multilayer structure using an inner core formed by crosslinking a composition is preferred because it has good durability and provides good shot sound and feel.

That is, as a rubber composition for obtaining a one-piece ball or an inner core, a polybutadiene containing 5 to 30% by weight of syndiotactic-1,2-polybutadiene and 40% by weight or more of cis-1,4-polybutadiene is used. The base rubber contains Gen rubber (hereinafter referred to as VCR) as an essential component,
Compared to conventional floating balls, the ball contains ultra-high molecular polyolefin particles with an average particle diameter of 50μ or less, an inorganic filler, a crosslinking monomer, and an initiator.
This is preferable because a floating golf ball having good durability and good hitting sound and hitting feeling can be obtained.

In the above rubber composition, VCR is used as an essential component of the base rubber because VCR contains syndiotactic-1,2-polybutadiene with high crystallinity and high melting point. Unlike when polybutadiene is used alone, it gives the golf ball appropriate hardness (ball compression) without adding a large amount of inorganic filler that increases specific gravity, and gives a suitable shot feel and sound. This is because durability can be improved.

A specific example of such a VCH is Ube Industries (
UBEPOL-VCR309 (trade name, composition: Herring diotactic-1,2-polybutadiene 9% by weight) manufactured by Co., Ltd.
, 89% by weight of cis-1,4-polybutadiene, 2% by weight of trans-1,4-polybutadiene), UBEPOL
-VCR412 (product name, composition Herring Diotactic-
There are commercially available products such as 12% by weight of 1,2-polybutadiene, 86% by weight of cis-1,4-polybutadiene, and 2% by weight of trans-1,4-;l:Rivkuziev.

The above-mentioned VCR is an essential rubber component in the above-mentioned rubber composition, and the more this VCR is contained in the base rubber, the better the physical properties of the golf ball will be obtained. Therefore, it is possible to use only this VCH as the base rubber, or from the viewpoint of processability and cost, natural rubber, cis-1,4-polybutadiene, styrene butadiene, etc. can be used for VCR with this VCR as an essential component. Rubber etc. may be blended.

When a base rubber is prepared by blending VCH with natural rubber, cis-1,4-polybutadiene, styrene-butadiene rubber, etc. as described above, it is preferable that the VCR contains 930% by weight or more of the base rubber. That is, it is preferable that VCH occupies 30 to 100 positive ff1% of the base rubber.

Fine particulate ultra-high molecular weight polyolefin with an average particle size of 50μ or less plays the role of a low specific gravity reinforcing filler, increases the hardness and durability of the golf ball, and improves the feel at impact,
To improve the sound of hitting a ball. As such fine particulate ultra-high molecular weight polyolefin, for example, Mitsui Petrochemical Industries, Ltd.
Miperon (trade name, average particle size 20 μm, molecular weight 20
Ultra-high molecular weight polyolefins in the form of fine particles of 0,000 or more are commercially available. And, such an average particle diameter is 50 μm
The amount of the fine-grain carbon ultra-high molecular weight polyolefin below is usually 10 to 40 parts by weight per 100 parts by weight of the base rubber.
Parts by weight are preferred.

Examples of inorganic fillers used include zinc oxide (ZnO), silicon oxide (Si02), calcium carbonate, and aluminum silicate. The main role of these is to increase the hardness and IH impact strength, increase the durability of the golf ball, and improve the feel and sound of the ball. Monoethylenically inert saturated carboxylic acids also function as metal salts of these acids and serve as crosslinking monomers to enable crosslinking of rubber compositions. If a large amount of these inorganic fillers is added, the hardness and impact hardness will increase, but the specific gravity will increase and the product will not float on water, so the amount of these inorganic fillers added should be
Usually, it is preferable to use 5 to 2 parts by weight per 100 parts by weight of the base rubber.

Crosslinking monomers crosslink rubber compositions to exhibit rebound resilience, etc., and give golf balls hardness, durability, and suitable shot feel and sound. For example, α, β-monoethylenically unsaturated carboxylic acids such as methacrylic acid and acrylic acid, their metal salts, polyfunctional methacrylic acid esters such as trimethylolpropane trimethacrylate, and polyfunctional acrylic acids such as trimethylolpropane triacrylate. Ester and the like are used, and the amount of these crosslinking monomers is preferably 5 to 25 parts by weight based on 100 parts by weight of the base rubber.

The initiator is used to initiate the polymerization of the crosslinking monomer to crosslink the rubber composition, and examples of such initiators include dicumyl peroxide, 2,2-di(tert), etc. -butylperoxy)butane,
A peroxide such as tert-butyl perbenzoate is used, and the amount of these peroxides is usually preferably 0.5 to 5 parts by weight per 100 parts by weight of the base rubber.

When the ball is made into a two-piece ball, the outer skin covering the inner core obtained by crosslinking the rubber composition is made of ionomer resin, transpolyisoprene, or polyurethane resin as a base material, and additives such as pigments are added as appropriate. Those added are preferred.

Figures 1 and 2 are diagrams showing an example of a golf ball according to the present invention. Figures 1 and 2 illustrate a one-piece ball, and Figure 1 is a front view thereof, and Figure 2 is a sectional view thereof. be.

In the figure, 1 is the golf ball body, 2 is the golf ball body 1
It is a dimple provided on the surface of. However, although 250 to 450 dimples 2 are normally provided as described above, FIGS. 1 and 2 show a case where the total number of dimples is 336.

The total dimple volume is determined by selecting an appropriate number of dimples (usually 24 to 48 dimples) from among the dimples provided on the surface of the golf ball.
(30 pieces in the example described later), cut the dimples in 1/1000 mm units in the depth direction, assume them to be truncated cones, add them to find the volume, and calculate the volume proportionally to the total number of dimples. This is what I asked for.

〔Example〕

Four types of floating golf balls having the specifications shown in Examples 1 to 4 below were prepared and compared with the balls of Examples 1 to 4, the balls of Comparative Examples 1 and 2, and the ball of Reference Example. The ball of Comparative Example 1 has the same dimple specifications as the conventional dimple specifications, with a dimple diameter of 3.4 mm and a total dimple volume of 34011 mm.
It is a one-piece floating golf ball with Ig@3 and a total number of dimples of 3361. The ball of Comparative Example 2 is a one-piece floating golf ball with a total dimple volume of 650 mm3, which is larger than the upper limit of 600n+n+3 of the present invention.The reference example is a thread-wound golf ball for rounds, and this ball has a specific gravity of 1.09. However, it does not float on water and cannot be used for water practice. Note that all the balls are large size balls, and the diameter is about 42.8 mm. Furthermore, all the formulations shown in Table 1 are based on parts by weight.

Example 1 A one-piece floating ball having a dimple diameter of 3.91, a total dimple volume of 450 mm3, and a total number of dimples of 3361 and a weight i1 was prepared using the formulation described in the column of Example 1 in Table 1.

Example 2 A dimple diameter of 3
．． 7n+m, total dimple volume 520fflI113,
A one-piece floating ball with a total of 392 dimples was produced.

Example 3 Inner core (diameter 3
8.3mm) with an outer skin based on Himilan 1707 (trade name, ionomer resin manufactured by DuPont Mitsui Polychemicals), dimple diameter 3.7, total dimple volume 520n+m3, total number of dimples 3921 (dimple specifications are A two-piece floating ball (same as in Example 2) was prepared.

Example 4 One-piece floating with a dimple diameter of 3.71, a total dimple volume of 520 mm, and a total number of dimples of 392 (the dimple specifications are the same as in Example 2) using the composition described in Example 4 in Table 1. A ball was made.

The above actual M% (4J) The floating golf balls of 1 to 4, the floating golf balls of Comparative Examples 1 to 2, and the round wound golf balls of Reference Examples were tested using a golf ball hitting tester (swing robot) manufactured by True Temper. , United States Golf Ball Association (USG)
A) OD S (Overall Distance
5 standard), we conducted a flight test by hitting with a No. 1 wood club at a head speed of 45 m/sec, and evaluated the difference in flight carry (distance) and trajectory height. are shown in Table 1. Note that the evaluation values shown in Table 1 are numerical values obtained by conducting tests on 20 balls of each type and evaluating the average value thereof.

As shown in Table 1, the trajectory of the ball of Comparative Example 1 increases significantly even before reaching the highest point and hops, resulting in a loss in flight distance (carry).
The trajectory was much higher than that of the reference example of a round wound thread ball. In addition, the total dimple volume is 15011
In the ball of Comparative Example 2, which was made very large (11113), the total dimple volume was too large, so no lift was applied to the ball, the ball became a ring ball and stalled, and the carry was also small.

On the other hand, the balls of Examples 1 to 4 all had trajectories that were very similar to the reference example round thread-wound balls, and their carry was also significantly higher than that of the balls of Comparative Examples 1 and 2.
The effects of the present invention are clearly evident.

〔Effect of the invention〕

As explained above, in the present invention, by finding the optimal total dimple volume and dimple diameter for a floating ball, it was possible to improve the trajectory performance of the floating ball and bring it closer to the trajectory shape of a round ball.

[Brief explanation of drawings]

FIG. 1 is a front view showing an example of a golf ball according to the present invention, and FIG. 2 is a sectional view thereof.

Claims (5)

[Claims] (1) Ball specific gravity is 1.0 or less and dimple diameter is 3
．． 5-4.0mm, total dimple volume 400-600
A floating practice golf ball measuring mm^3. (2) The floating practice golf ball according to claim 1, wherein the total number of dimples is 336. (3) The floating practice golf ball according to claim 1, wherein the total number of dimples is 392. (4) The ball contains a base rubber whose essential component is polybutadiene rubber containing 5 to 30% by weight of syndiotactic-1,2-polybutadiene and 40% by weight of cis-1,4-polybutadiene rubber, and average particles. Claim No. 1, which is an integrally molded one-piece ball obtained by crosslinking a rubber composition containing a fine particulate ultra-high molecular weight polyolefin having a diameter of 50 μm or less, an inorganic filler, a crosslinkable monomer, and an initiator. The floating practice golf ball according to item 1, item 2, or item 3. (5) A base rubber whose essential components are polybutadiene rubber in which the ball contains 5 to 30% by weight of syndiotactic-1,2-polybutadiene and 40% by weight of cis-1,4-polybutadiene rubber, and average particles. An inner core obtained by crosslinking a rubber composition containing a fine particulate ultra-high molecular weight polyolefin having a diameter of 50 μm or less, an inorganic filler, a crosslinking monomer, and an initiator, and an ionomer resin, transpolyisoprene, or polyurethane resin. Claim 1, which is a ball with a multilayer structure using an outer skin based on
The floating practice golf ball according to item 2 or 3.