Golf balls with rubber cores

Abstract

We offer golf balls with rubber cores. [Solution] The golf ball comprises a sphere core layer 1 and a sphere shell layer 2 covering the outside of the sphere core, with a plurality of regularly arranged recesses 20 formed on the outer surface of the sphere shell layer. The sphere core layer is made of a rubber material containing butadiene homopolymer rubber and auxiliary rubber. Taking the total weight of the rubber material as 100% by weight, the content of butadiene homopolymer rubber is 10% to 95% by weight. The auxiliary rubber is selected from the group consisting of styrene-butadiene rubber, nitrile rubber, butyl rubber, bromide butyl rubber, and ethylene propylene rubber. According to the TPX3007 (Rev.2.1) standard for ball initial velocity testing methods jointly established by the Royal and Advanced Golf Club of St. British Golf (R&A) and the United States Golf Association, the contact time of the golf ball is 300 μs (microseconds) to 600 μs.

Description

Technical Field

[0001] The present invention relates to a golf ball, and more particularly to a golf ball with a rubber core.

Background Art

[0002] "Golf" has always been regarded as a leisure activity of the Western aristocracy. In recent years, with the improvement of people's living standards and the emphasis on leisure life, people of all occupations, all age groups, both young and old, both men and women are becoming enthusiastic about golf, and golf is gradually becoming a national sport.

[0003] The performance of the golf ball itself affects the flight direction and the carry distance of the golf ball after being hit, and further determines the controllability of the ball. An excellent golf ball has a high initial velocity, a good feel, and high properties such as spin.

[0004] However, because the coefficient of restitution (COR) of the current golf ball is relatively high, the carry distance of the golf ball is gradually increasing. In order to assess the player's ability, it is necessary to continuously increase the total length of the fairway, which causes many difficulties.

[0005] Therefore, both the United States Golf Association (USGA) and the Royal and Ancient Golf Club of St Andrews (also known as The R&A) in the UK have decided to completely ban the existing golf balls from 2028. According to the new rules, when a golf ball is hit under the conditions of a test speed of 125 miles per hour (mph), a launch angle of 11 degrees, and a spin rate of 2,200 revolutions per minute (rpm), the carry distance must not exceed 317 yards.

[0006] Therefore, how to improve the material to provide a golf ball that meets the new competition rules has become one of the important issues to be solved in this industry.

Summary of the Invention

[0007] The technological problem that this invention aims to solve is to provide a golf ball with a rubber core, addressing the shortcomings of conventional technology. [Means for solving the problem]

[0008] To solve the above technical problems, one of the technical means employed by this invention is to provide a golf ball with a rubber core. The golf ball includes a sphere core layer and a sphere shell layer covering the outside of the sphere core, and the outer surface of the sphere shell layer is formed such that a plurality of recesses are regularly arranged. The sphere core layer is made of a rubber material including butadiene homopolymer rubber and auxiliary rubber. Taking the total weight of the rubber material as 100% by weight, the content of butadiene homopolymer rubber is 10% to 95% by weight. The auxiliary rubber is selected from the group consisting of styrene-butadiene rubber, nitrile rubber, butyl rubber, bromide butyl rubber, and ethylene propylene rubber. According to the ball initial velocity test method standard TPX3007 (Rev.2.1) jointly established by the British Golf Association and the United States Golf Association, the contact time of the golf ball is 300 μs (microseconds) to 600 μs.

[0009] In one embodiment, when a golf ball is struck under the conditions of a test speed of 115 miles per hour (mph), a launch angle of 12.5 degrees, and a spin rate of 2,600 rpm, the distance the golf ball travels in the air is less than 270 yards.

[0010] In one embodiment, with the total weight of the rubber material being 100% by weight, the content of butadiene homopolymer rubber is 50% to 95% by weight.

[0011] In one embodiment, the number-average molecular weight of the butadiene homopolymer rubber is 50,000 g / mol to 2,000,000 g / mol.

[0012] In one embodiment, the number-average molecular weight of the auxiliary rubber is 25,000 g / mol to 2,500,000 g / mol.

[0013] In one embodiment, the auxiliary rubber is desulfurized rubber.

[0014] In one embodiment, the ratio of the contact time, measured according to the TPX3007 (Rev.2.1) standard jointly established by the British Golf Association and the United States Golf Association, to the coefficient of restitution, measured according to the TPX3009 (Rev.2.0) standard jointly established by the British Golf Association and the United States Golf Association, is 560.5 to 600.

[0015] In one embodiment, the butadiene homopolymer rubber and auxiliary rubber are present in the rubber material in the form of a continuous phase.

[0016] In one embodiment, the auxiliary rubber is dispersed in the form of a dispersed phase within a homopolymer rubber of butadiene, which is present in the form of a continuous phase.

[0017] In one embodiment, the volume ratio of the core layer in a golf ball is 50% to 98%. [Effects of the Invention]

[0018] One of the advantageous effects of this invention is that, due to the technical features of the rubber-cored golf ball according to this invention, "the rubber material includes butadiene homopolymer rubber and auxiliary rubber" and "the auxiliary rubber is selected from the group consisting of styrene-butadiene rubber, nitrile rubber, butyl rubber, bromide butyl rubber, and ethylene propylene rubber," the contact time and coefficient of restitution when the ball is struck can be reduced, thereby shortening the aerial flight distance (carry) of the golf ball. [Brief explanation of the drawing]

[0019] [Figure 1] This is a three-dimensional diagram of a rubber-cored golf ball according to the present invention. [Figure 2] This is a cross-sectional view of a rubber-cored golf ball according to the first embodiment of the present invention. [Figure 3] This is a cross-sectional view of a rubber-cored golf ball according to the second embodiment of the present invention.

Best Mode for Carrying Out the Invention

[0020] In order to further deepen the understanding of the features and technical content of the present invention, please refer to the following detailed description of the present invention and the attached drawings. However, the attached drawings provided are only used for reference and explanation, and do not limit the scope of the claims of the present invention.

[0021] Hereinafter, the implementation method of the "golf ball with a rubber core" according to the present invention will be described according to a specific embodiment. Those skilled in the art can understand the advantages and effects of the present invention based on the content disclosed in this specification. The present invention can be implemented or applied by other different specific embodiments, and for each detail in this specification, various modifications and changes can be made based on different viewpoints and uses without departing from the concept of the present invention. Also, it should be noted in advance that the attached drawings of the present invention are only simple schematic explanations and are not drawn based on actual sizes. It is declared in advance that although the technical content of the present invention will be described in more detail based on the following embodiments, the disclosed content does not limit the protection scope of the present invention. Also, the term "or" used in this specification may include any one or a combination of multiple items listed in relation according to the actual situation.

[0022] The present invention provides a golf ball that can meet new regulations. The present invention can change the characteristics of the golf ball at the moment of hitting by adjusting the material of the ball core layer of the golf ball, and further shorten the flight distance of the golf ball in the air.

[0023] The aerial flight distance of a golf ball, also known as carry, refers to the distance the hit ball travels until it lands on the ground. It has a positive correlation with the initial velocity of the golf ball after it is hit. However, the aerial flight distance of a golf ball may be affected by wind direction and terrain. Therefore, in this specification, first, the relationship between the material of the golf ball's core layer and the coefficient of restitution and contact time after hitting the golf ball will be examined. After the material selection is completed, the aerial flight distance of the golf ball will be measured on-site.

[0024] Upon further analysis, it can be seen that the initial velocity of a golf ball is affected by the test velocity, launch angle, contact time, and coefficient of restitution of the golf ball. Generally speaking, the most intuitive way to lower the initial velocity of a golf ball is to lower the coefficient of restitution. However, the coefficient of restitution of most commercially available materials has a negative correlation with the contact time. When the coefficient of restitution of a golf ball decreases, the contact time when hitting the ball becomes longer, so this point needs to be considered together.

[0025] The present invention has found that by improving the material of the core layer, the coefficient of restitution can be made to have a substantially positive correlation with the contact time. Also, since the contact time can be shortened while reducing the coefficient of restitution of the golf ball, the effect of reducing the initial velocity and aerial flight distance of the golf ball after hitting can be obtained.

[0026] To quantify the performance of the golf ball of the present invention, when the golf ball of the present invention is hit at a test velocity of 115 miles per hour (mph), a launch angle of 12.5 degrees, and a rotation speed of 2,600 rpm, the aerial flight distance is less than 270 yards. Furthermore, according to the standard TPX3007 (Rev. 2.1) of the test method for initial velocity jointly established by the R&A (Royal & Ancient Golf Club of St Andrews) and the USGA (United States Golf Association), the contact time of the golf ball of the present invention is less than 440 microseconds (μs).

[0027] [First Embodiment] Referring together to Figures 1 and 2, the golf ball G according to the first embodiment of the present invention includes a spherical core layer 1 and a spherical shell layer 2 that completely covers the spherical core layer 1. Based on the total volume of the golf ball, the volume ratio of the spherical core layer 1 in the golf ball is 50% to 98%, for example, 60%, 70%, 80%, or 90%.

[0028] The sphere core layer 1 is mainly made of rubber material, which includes butadiene homopolymer rubber and auxiliary rubber. Taking the total weight of the rubber material as 100% by weight, the content of butadiene homopolymer rubber is 10% to 95% by weight.

[0029] If the rubber material contains only butadiene homopolymer rubber, the contact time when the golf ball is struck will be long. This invention reduces the coefficient of restitution of the golf ball and the contact time when the ball is struck by adding an auxiliary rubber, thereby giving the golf ball the required characteristics. In other words, the design concept of this invention is to achieve the effect of reducing the coefficient of restitution of the golf ball and the contact time when the ball is struck by blending different rubber components.

[0030] Specifically, the auxiliary rubber may be selected from the group consisting of styrene-butadiene rubber (SBR), nitrile rubber (NBR), butyl rubber (IIR), butyl bromide rubber (BIIR), and ethylene propylene rubber (EPDM), but the present invention is not limited thereto.

[0031] The properties (such as molecular weight) of the butadiene homopolymer rubber and auxiliary rubber also affect the properties of the sphere core layer 1. Experimental measurements have shown that the number-average molecular weight of the butadiene homopolymer rubber is preferably 50,000 g / mol to 2,000,000 g / mol, and the number-average molecular weight of the auxiliary rubber is preferably 25,000 g / mol to 2,500,000 g / mol, however, this invention is not limited to these values.

[0032] In one embodiment, the number-average molecular weight of the butadiene homopolymer rubber may be 100,000 g / mol, 200,000 g / mol, 300,000 g / mol, 400,000 g / mol, 500,000 g / mol, 600,000 g / mol, 700,000 g / mol, 800,000 g / mol, 900,000 g / mol, 1,000,000 g / mol, 1,100,000 g / mol, 1,200,000 g / mol, 1,300,000 g / mol, 1,400,000 g / mol, 1,500,000 g / mol, 1,600,000 g / mol, 1,700,000 g / mol, 1,800,000 g / mol, or 1,900,000 g / mol.

[0033] In one embodiment, the number-average molecular weight of the auxiliary rubber is 50,000 g / mol, 100,000 g / mol, 200,000 g / mol, 300,000 g / mol, 400,000 g / mol, 500,000 g / mol, 600,000 g / mol, 700,000 g / mol, 800,000 g / mol, 900,000 g / mol, 1,000,000 g / mol, 1,100,000 g / mol, 1,200,000 g / mol. It may be 1,300,000 g / mol, 1,400,000 g / mol, 1,500,000 g / mol, 1,600,000 g / mol, 1,700,000 g / mol, 1,800,000 g / mol, 1,900,000 g / mol, 2,000,000 g / mol, 2,100,000 g / mol, 2,200,000 g / mol, 2,300,000 g / mol, or 2,400,000 g / mol.

[0034] In one embodiment, the butadiene homopolymer rubber and the auxiliary rubber are uniformly mixed and present in the rubber material in the form of a continuous phase. In another embodiment, the auxiliary rubber may be dispersed in the butadiene homopolymer rubber present in the form of a continuous phase, in the form of a dispersed phase. By adjusting the distribution of the rubber components in the sphere core material, the contact time and impact characteristics when hitting a golf ball can also be adjusted.

[0035] To avoid the problem of material separation due to mismatch, which can cause the golf ball to break after being struck, butadiene homopolymer rubber can be selected as the main component of the rubber material to improve the stability of the golf ball structure. In other words, the content of butadiene homopolymer rubber can be controlled to be greater than the content of auxiliary rubber.

[0036] With the total weight of the rubber material being 100% by weight, the butadiene homopolymer rubber content is 50% to 95% by weight, for example, 55%, 60%, 65%, 70%, 75%, 80%, 85%, or 90% by weight.

[0037] Furthermore, the rubber material may also contain recycled rubber (desulfurized rubber). Compared to synthetic rubber, recycled rubber has a slightly lower coefficient of restitution due to the desulfurization process, which can shorten the contact time when hitting a golf ball. In addition, the addition of recycled rubber can reduce the amount of rubber material used, thereby reducing costs.

[0038] In actual application, the material forming the core layer may further contain a crosslinking agent and a filler. Specific examples of crosslinking agents include zinc acrylate and magnesium acrylate. The filler may be dispersed in the rubber material as a dispersed phase. The filler may be a material with a relatively low specific gravity. In this way, after adding the filler, the amount of rubber material added can be slightly reduced, thereby reducing costs and providing the effect of adjusting the properties of the golf ball.

[0039] Specifically, the specific gravity of the filler is lower than that of the rubber material. The filler may exist in the form of fibrous structures, round particles, angular particles, or sheet structures, but the present invention is not limited thereto. The type of filler may be zinc oxide, barium sulfate, or other high-density metal powders (such as tungsten powder), but the present invention is not limited thereto.

[0040] Multiple circular recesses 20, which function as dimples, are formed on the outer surface of the spherical shell layer 2 in a regularly arranged manner. The arrangement of the recesses 20 causes the airflow to form a turbulent boundary layer on the spherical surface, reducing the depletion region behind the sphere and further reducing air resistance.

[0041] The material of the spherical shell layer 2 may be an elastomer or a polymer. The elastomer may be a thermoplastic polyurethane (TPU), a thermosetting polyurethane elastomer (TSU), or a polyether ester elastomer (TPEE). The polymer may be an ionomer (e.g., Surlyn resin) or an ethylene-methacrylic acid copolymer, but the present invention is not limited thereto.

[0042] [Second Embodiment] Referring together to Figures 1 and 3, the golf ball G according to the second embodiment of the present invention comprises a sphere core layer 1, an interlayer layer 3, and a sphere shell layer 2. The interlayer layer 3 is positioned between the sphere shell layer 2 and the sphere core layer 1. The structure and materials of the sphere core layer 1 and the sphere shell layer 2 are similar to those of the first embodiment and will not be described again here.

[0043] The interlayer 3 can be selectively fixed between the sphere core layer 1 and the sphere shell layer 2 via an adhesive layer. The material of the interlayer 3 may be a thermosetting polyurethane elastomer (TSU), a polyether ester elastomer (TPEE), an ionomer (for example, a resin from Dow's HPF series), or a thermoplastic.

[0044] For example, the thickness of the interlayer 3 may be 0.5 mm to 5.0 mm, and may be, for example, 0.6 mm, 0.8 mm, 1.0 mm, 1.2 mm, 1.4 mm, 1.6 mm, 1.8 mm, 2.0 mm, 2.2 mm, 2.4 mm, 2.6 mm, 2.8 mm, 3.0 mm, 3.2 mm, 3.4 mm, 3.6 mm, 3.8 mm, 4.0 mm, 4.2 mm, 4.4 mm, 4.6 mm, or 4.8 mm.

[0045] To demonstrate that the golf ball of this invention can shorten the contact time when struck, golf balls of samples 1 to 7 were manufactured according to the structure shown in the first embodiment (see Figure 2). In all of the golf balls of samples 1 to 7, the core layer was covered with thermoplastic polyurethane to form the shell layer. The difference between them is that different rubber materials were used to manufacture the core layer.

[0046] In Samples 1 and 2, the core layer material consists solely of butadiene homopolymer rubber. The butadiene homopolymer rubber may be either butadiene homopolymer rubber catalyzed by a neodymium catalyst (NdBR) or butadiene homopolymer rubber catalyzed by a cobalt catalyst (KBR). The number-average molecular weight of the butadiene homopolymer rubber ranged from 50,000 g / mol to 2,000,000 g / mol. In the samples of this invention, the number-average molecular weight of the butadiene homopolymer rubber used was 400,000 g / mol. In Sample 1, pentachlorothiophenol zinc salt (ZnPCTP) was further added to the rubber material to improve the flexibility and elasticity of the golf ball core layer.

[0047] In samples 3-5, the sphere core layer material included butadiene homopolymer rubber and auxiliary rubber. The auxiliary rubber was styrene-butadiene rubber (SBR), and its number-average molecular weight ranged from 25,000 g / mol to 2,500,000 g / mol. In the samples of the present invention, the number-average molecular weight of the auxiliary rubber used was 100,000 g / mol in all cases.

[0048] In Sample 6, the core layer material contains only auxiliary rubber (styrene-butadiene rubber (SBR)).

[0049] In Sample 7, the core layer material contained butadiene homopolymer rubber and desulfurized rubber. The desulfurized rubber was derived from tires and consisted of styrene-butadiene rubber, polybutadiene rubber, and natural rubber. The number-average molecular weight of the desulfurized rubber ranged from 25,000 g / mol to 2,500,000 g / mol.

[0050] Table 1 shows that the compression hardness of golf balls samples 1-7 was measured using a compression tester manufactured by Precision ADCs, and the Shore hardness (Shore C) of the golf balls was measured according to the ASTM-D2240 standard test method. Furthermore, the coefficient of restitution of the golf balls was measured at average test speeds of 125 ft / s and 175 ft / s, respectively, using a coefficient of restitution tester manufactured by Precision ADCs.

[0051] Table 2 shows the initial velocity and contact time of golf balls samples 1-7, measured according to the TPX3007 (Rev.2.1) standard jointly established by the British Golf Association and the United States Golf Association. Furthermore, the coefficient of restitution of samples 1-7 at an average test velocity of 143 ft / s was measured according to the TPX3009 (Rev.2.0) standard jointly established by the British Golf Association and the United States Golf Association. The values ​​shown in Table 2 are the average values ​​after 12 tests.

[0052] [Table 1]

[0053] [Table 2]

[0054] The results in Tables 1 and 2 show that when the core layer material contains butadiene homopolymer rubber and auxiliary rubber, both the coefficient of restitution and contact time of the golf ball decrease as the auxiliary rubber content increases, indicating a nearly positive correlation between the coefficient of restitution and contact time. A decrease in both the coefficient of restitution and contact time is expected to lead to a decrease in the airborne flight distance of the golf ball.

[0055] Similar effects can be obtained when recycled desulfurized rubber is incorporated. Compared to the sample without added desulfurized rubber, the golf ball in sample 7 has a lower coefficient of restitution and contact time. Therefore, using recycled desulfurized rubber instead of auxiliary rubber can also shorten the airborne distance of the golf ball.

[0056] Furthermore, to distinguish it from commercially available materials where the coefficient of restitution and contact time have an almost negative correlation, Table 2 shows the ratio of contact time to the coefficient of restitution, demonstrating that the relationship between the coefficient of restitution and contact time can be adjusted by selecting the material of this invention. From the results in Table 2, it was found that the ratio of contact time (TPX3007 (Rev.2.1)) to the coefficient of restitution (TPX3009 (Rev.2.0)) is between 560.5 and 600.

[0057] After the material selection was complete, golf balls samples 1-7 were launched into the field, and their aerial flight distance (carry) was measured. The measurements were conducted with a fixed speed of 115 mph and a spin rate of 2600 rpm, and the results are shown in Table 3.

[0058] [Table 3]

[0059] As can be seen from the results in Table 3, the aerial distance of the golf ball gradually decreases as the content of the auxiliary rubber increases. Mixing in recycled desulfurized rubber also yields good results. Therefore, this invention can achieve the effect of shortening the aerial distance of the golf ball to meet the regulations of the new competition system by adding auxiliary rubber.

[0060] [Advantageous effects of the embodiment] One of the advantageous effects of this invention is that, due to the technical features of the rubber-cored golf ball according to this invention, "the rubber material includes butadiene homopolymer rubber and auxiliary rubber" and "the auxiliary rubber is selected from the group consisting of styrene-butadiene rubber, nitrile rubber, butyl rubber, bromide butyl rubber, and ethylene propylene rubber," the contact time and coefficient of restitution when the ball is struck can be reduced, thereby shortening the flight distance of the golf ball.

[0061] The information disclosed above represents only preferred and implementable embodiments of the present invention, and the claims of the present invention are not limited thereto. Therefore, any equivalent technical modifications made using the description and drawings of the present invention are all included within the scope of the claims of the present invention. [Explanation of symbols]

[0062] G...Golf ball 1... Nuclear layer 2...spherical shell layer 20...recess 3...Intermediate film layer

Claims

1. A golf ball comprising a sphere core layer and a sphere shell layer covering the outside of the sphere core, wherein a plurality of recesses are formed on the outer surface of the sphere shell layer so as to be regularly arranged, The sphere core layer is formed of a rubber material containing butadiene homopolymer rubber and auxiliary rubber, wherein the content of butadiene homopolymer rubber is 10% to 90% by weight, with the total weight of the rubber material being 100% by weight, and the auxiliary rubber is selected from the group consisting of styrene-butadiene rubber, nitrile rubber, butyl rubber, bromide butyl rubber, and ethylene propylene rubber. According to TPX3007 (Rev. 2.1), a standard for testing ball initial velocity jointly established by the Royal and Advanced Golf Club of St. David (R&A) and the United States Golf Association, the contact time of the golf ball is 300 μs (microseconds) to 600 μs. A golf ball characterized in that the ratio of the contact time, measured according to the standard TPX3007 (Rev. 2.1) jointly established by the British Golf Association and the United States Golf Association, to the coefficient of restitution, measured according to the standard TPX3009 (Rev. 2.0) jointly established by the British Golf Association and the United States Golf Association, is 560.5 to 600.

2. The golf ball according to claim 1, wherein an interlayer is further disposed between the spherical shell layer and the spherical core layer.

3. The golf ball according to claim 1, wherein when the golf ball is struck at a test speed of 115 miles per hour (mph), a launch angle of 12.5 degrees, and a spin rate of 2,600 rpm, the aerial distance (carry) of the golf ball is less than 270 yards.

4. The golf ball according to claim 1, wherein the total weight of the rubber material is 100% by weight, and the content of the butadiene homopolymer rubber is 50% to 90% by weight.

5. The number-average molecular weight of the butadiene homopolymer rubber is 50,000 g / mol to 2,000,000 g / mol, as described in claim 1.

6. The golf ball according to claim 1, wherein the number-average molecular weight of the auxiliary rubber is 25,000 g / mol to 2,500,000 g / mol.

7. The golf ball according to claim 1, wherein the auxiliary rubber is desulfurized rubber.

8. The golf ball according to claim 1, wherein the butadiene homopolymer rubber and the auxiliary rubber are present in the rubber material in the form of a continuous phase.

9. The golf ball according to claim 1, wherein the auxiliary rubber is dispersed in the butadiene homopolymer rubber, which is present in the form of a continuous phase.

10. The golf ball according to claim 1, wherein the volume ratio of the sphere core layer in the golf ball is 50% to 98%.

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