Rubber-core golf ball

Abstract

To provide a rubber-core golf ball.SOLUTION: A golf ball includes a spherical core layer, and a spherical shell layer covering the outside of the spherical core layer. The spherical core layer is formed of a rubber material containing a homopolymer rubber of butadiene and an auxiliary rubber. With a total weight of the rubber material set to 100 wt.%, the content of the homopolymer rubber of butadiene is 10 wt.% to 95 wt.%. The auxiliary rubber is selected from a group consisting of styrene-butadiene rubber, nitrile rubber, butyl rubber, brominated butyl rubber, and ethylene propylene rubber. According to the standard TPX3007 (Rev. 2.1) of the ball initial velocity test method jointly established by the Royal and Ancient Golf Club of St Andrews (R&A) and the United States Golf Association, the contact time of a golf ball is 300 μs (microseconds) to 600 μs.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Golf has always been considered a leisure activity for the Western aristocracy. In recent years, with the improvement of people's living standards and the increased emphasis on leisure, people of all ages and professions have become fascinated with golf, and it has gradually become a national sport.

[0003] The performance of a golf ball itself affects the direction and carry of the ball after impact, and also determines the controllability of the ball. A good golf ball has high initial velocity, a good feel, and excellent spin.

[0004] However, because the coefficient of restitution (COR) of modern golf balls is relatively high, the distance a golf ball can travel in the air is gradually increasing. To assess a player's ability, the total length of the fairway must be continuously increased, which creates many challenges.

[0005] As a result, both the United States Golf Association (USGA) and the Royal and Anglican Golf Association (also known as the R&A) have decided to completely ban existing golf balls from 2028. According to the new rules, a golf ball cannot travel more than 317 yards in the air when hit at a test speed of 125 miles per hour (mph), with a launch angle of 11 degrees and a spin rate of 2,200 rpm.

[0006] Therefore, one of the important issues that this project aims to solve is how to improve materials to provide golf balls that comply with the new rules. Summary of the Invention [Problem to be solved by the invention]

[0007] The technical problem to be solved by the present invention is to provide a golf ball with a rubber core in response to the shortcomings of the prior art. [Means for solving the problem]

[0008] To solve the above technical problems, one technical solution adopted by the present invention is a golf ball with a rubber core. The golf ball includes a core layer and a shell layer surrounding the core. The core layer is formed of a rubber material containing a butadiene homopolymer rubber and a secondary rubber. The butadiene homopolymer rubber content is 10% to 95% by weight, with the total weight of the rubber material being 100% by weight. The secondary rubber is selected from the group consisting of styrene-butadiene rubber, nitrile rubber, butyl rubber, brominated butyl rubber, and ethylene propylene rubber. According to the TPX3007 (Rev. 2.1) standard for testing ball initial velocity jointly established by the British Golf Association and the United States Golf Association, the contact time of a golf ball is 300 μs to 600 μs.

[0009] In one embodiment, the golf ball travels less than 270 yards through the air when hit 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.

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

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

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

[0013] In some embodiments, the secondary rubber is devulcanized rubber.

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

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

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

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

[0018] One of the advantageous effects of the present invention is that the rubber core golf ball of the present invention has the technical features that "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, brominated butyl rubber, and ethylene propylene rubber," which reduce the contact time and restitution coefficient when hitting the ball, thereby shortening the golf ball's flight distance (carry). [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a three-dimensional view of a golf ball with a rubber core according to the present invention. [Figure 2] 1 is a cross-sectional view of a golf ball with a rubber core according to a first embodiment of the present invention. [Figure 3] FIG. 2 is a cross-sectional view of a rubber-cored golf ball according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] To better understand the features and technical contents of the present invention, please refer to the following detailed description of the present invention and the accompanying drawings, which are provided for reference and explanation purposes only and do not limit the scope of the present invention.

[0021] The following describes the implementation of the "rubber core golf ball" according to the present invention through certain specific embodiments, and those skilled in the art will be able to understand the advantages and effects of the present invention based on the content disclosed herein. The present invention can be implemented or applied in other different specific embodiments, and various modifications and changes can be made to the details herein based on different perspectives and applications without departing from the concept of the present invention. It should be noted that the accompanying drawings of the present invention are merely schematic illustrations and are not drawn to actual size. It should be noted that the technical content of the present invention will be described in more detail based on the following embodiments, but the disclosed content does not limit the scope of protection of the present invention. The term "or" used in the present specification may include any one or more combinations of the related listed items depending on the actual situation.

[0022] The present invention provides a golf ball that complies with the new regulations. By adjusting the material of the core layer of the golf ball, the characteristics of the golf ball can be changed at the moment of impact, and the flight distance of the golf ball can be shortened.

[0023] The flight distance of a golf ball, also known as carry, refers to the distance the ball travels from the moment it is hit until it hits the ground. It is positively correlated with the initial velocity of the golf ball after it is hit. However, the flight distance of a golf ball can be affected by wind direction and terrain. Therefore, this specification first examines the relationship between the material of the core layer of a golf ball and the coefficient of restitution and contact time after the golf ball is hit. After the material selection is complete, the flight distance of the golf ball is measured on-site.

[0024] Further analysis reveals that the initial velocity of a golf ball is affected by the test speed, launch angle, contact time, and the golf ball's coefficient of restitution. Generally speaking, the most intuitive way to reduce the initial velocity of a golf ball is to reduce the coefficient of restitution. However, the coefficient of restitution of most commercially available materials is negatively correlated with contact time. As the coefficient of restitution of a golf ball decreases, the contact time when the ball is struck increases, so this must also be taken into consideration.

[0025] The present invention has found that by improving the material of the core layer, it is possible to make the restitution coefficient almost positively correlate with the contact time. Furthermore, by lowering the restitution coefficient of the golf ball while shortening the contact time, it is possible to reduce the initial velocity of the golf ball after hitting and the flight distance in the air.

[0026] To quantify the performance of the golf balls of the present invention, the golf balls of the present invention have an airborne distance of less than 270 yards when hit 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. Furthermore, the golf balls of the present invention have a contact time of less than 440 microseconds (μs) according to the TPX3007 (Rev. 2.1) standard for initial velocity testing established jointly by the British Golf Association and the United States Golf Association.

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

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

[0029] If a rubber material contains only butadiene homopolymer rubber, the contact time when the golf ball is hit will be long. In the present invention, by adding an auxiliary rubber, the restitution coefficient of the golf ball and the contact time when the ball is hit can be reduced, thereby providing the golf ball with the desired properties. In other words, the design concept of the present invention is to achieve the effect of reducing the restitution coefficient of the golf ball and the contact time when the ball is hit 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), brominated butyl 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 the auxiliary rubber also affect the properties of the 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, but the present invention is not limited thereto.

[0032] In some embodiments, 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 some embodiments, 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, 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, 2,000,000 g / mol, 2,100,000 g / mol, 2,200,000 g / mol, 3,300,000 g / mol, 4,400,000 g / mol, 5,500,000 g / mol, 6,500,000 g / mol, 7,000,000 g / mol, 8,000,000 g / mol, 9,000,000 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, 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, 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 in the form of a dispersed phase, which is present in the form of a continuous phase. By adjusting the distribution of the rubber components in the core material, the contact time and impact characteristics when hitting the golf ball can also be adjusted.

[0035] To avoid the problem of materials being separated due to incompatibility and causing breakage after hitting the golf ball, butadiene homopolymer rubber can be selected as the main component of the rubber material to improve the stability of the golf ball structure, i.e., the content of butadiene homopolymer rubber can be controlled to be greater than the content of auxiliary rubber.

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

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

[0038] In practical application, the material forming the core layer may further include 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 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 be in the form of a fiber structure, round particles, angular particles, or sheet structure, but the present invention is not limited thereto. The type of filler may be zinc oxide, barium sulfate, or other high-density metal powder (such as tungsten powder), but the present invention is not limited thereto.

[0040] A plurality of circular recesses 20 that function as dimples are regularly arranged on the outer surface of the spherical shell layer 2. 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 spherical surface and further reducing air resistance.

[0041] The material of the spherical shell layer 2 may be an elastomer or a high molecular weight polymer. The elastomer may be a thermoplastic polyurethane elastomer (TPU), a thermoset polyurethane elastomer (TSU), or a thermoplastic polyester elastomer (TPEE). The high molecular weight polymer may be an ionomer (e.g., Surlyn) or an ethylene-methacrylic acid copolymer, although the present invention is not limited thereto.

[0042] [Second embodiment] 1 and 3, a golf ball G according to a second embodiment of the present invention comprises a spherical core layer 1, an intermediate film layer 3, and a spherical shell layer 2. The intermediate film layer 3 is disposed between the spherical shell layer 2 and the spherical core layer 1. The structures and materials of the spherical core layer 1 and the spherical shell layer 2 are similar to those of the first embodiment, and therefore will not be described again here.

[0043] The intermediate film layer 3 can be selectively fixed between the core layer 1 and the shell layer 2 via an adhesive layer. The material of the intermediate film layer 3 may be a thermosetting polyurethane elastomer (TSU), a polyether ester elastomer (TPEE), an ionomer (e.g., HPF series resins manufactured by Dow), or a thermoplastic plastic.

[0044] For example, the thickness of the intermediate film layer 3 may be 0.5 mm to 5.0 mm, 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 prove that the golf ball of the present invention can shorten the contact time when hit, golf balls of Samples 1 to 7 were manufactured according to the structure shown in the first embodiment (see FIG. 2). All of the golf balls of Samples 1 to 7 had a spherical core layer covered with thermoplastic polyurethane to form a spherical shell layer. The difference between them is that the spherical core layer was manufactured using a different rubber material.

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

[0047] In Samples 3 to 5, the core layer material included a butadiene homopolymer rubber and a secondary rubber. The secondary rubber was styrene-butadiene rubber (SBR), and the number average molecular weight of the secondary rubber 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 secondary rubber used was 100,000 g / mol.

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

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

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

[0051] In Table 2, the initial velocity and contact time of the golf balls of Samples 1 to 7 were measured in accordance with the TPX3007 (Rev. 2.1) standard jointly established by the Royal Golf Association and the United States Golf Association. In addition, the coefficient of restitution of Samples 1 to 7 was measured at an average test velocity of 143 ft / s in accordance with the TPX3009 (Rev. 2.0) standard jointly established by the Royal 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, as the content of auxiliary rubber increases, the restitution coefficient and contact time of the golf ball both decrease, and there is an almost positive correlation between the restitution coefficient and contact time of the golf ball. If both the restitution coefficient and contact time decrease, it is expected that the flight distance of the golf ball will also decrease.

[0055] Similar effects were obtained when recycled devulcanized rubber was added. Compared to the sample without devulcanized rubber, the golf ball of Sample 7 had a lower restitution coefficient and contact time. Therefore, using recycled devulcanized rubber instead of auxiliary rubber can also have the effect of shortening the flight distance of the golf ball.

[0056] Furthermore, to distinguish from commercially available materials, for which the restitution coefficient and contact time are almost negatively correlated, Table 2 shows the ratio of contact time to restitution coefficient, demonstrating that the relationship between restitution coefficient and contact time can be adjusted by selecting the material of the present invention. The results in Table 2 show that the ratio of contact time (TPX3007 (Rev. 2.1)) to restitution coefficient (TPX3009 (Rev. 2.0)) is 560.5 to 600.

[0057] After the material selection was completed, golf balls of Samples 1 to 7 were put into the field and the carry distance of the golf balls was measured. The measurement was carried out by flight tests with a fixed speed of 115 mph and a fixed 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, as the content of auxiliary rubber increases, the flight distance of the golf ball gradually decreases. A good effect can also be obtained by adding recycled devulcanized rubber. Therefore, the present invention can achieve the effect of shortening the flight distance of the golf ball by adding auxiliary rubber, so as to meet the regulations of the new playing system.

[0060] [Advantageous Effects of the Embodiments] One of the advantageous effects of the present invention is that the rubber core golf ball of the present invention has the technical features that "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, brominated butyl rubber, and ethylene propylene rubber," which reduce the contact time and restitution coefficient when hitting the ball, thereby shortening the golf ball's flight distance.

[0061] The above disclosure is merely a preferred embodiment of the present invention, and the scope of the claims of the present invention is not limited thereto. Therefore, any equivalent technical modifications made by utilizing the specification and drawings of the present invention are included in 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 spherical core layer and a spherical shell layer covering the outside of the spherical core, the core layer is formed of a rubber material containing a butadiene homopolymer rubber and an auxiliary rubber, the content of the butadiene homopolymer rubber being 10% by weight to 95% by weight, with the total weight of the rubber material being 100% by weight, and the auxiliary rubber being selected from the group consisting of styrene-butadiene rubber, nitrile rubber, butyl rubber, brominated butyl rubber, and ethylene propylene rubber; A golf ball characterized in that the contact time of the golf ball is 300 μs (microseconds) to 600 μs according to the standard TPX3007 (Rev. 2.1) for testing ball initial velocity established jointly by The Royal and American Golf Association (R&A) and the United States Golf Association.

2. 10. The golf ball of claim 1, wherein the golf ball has a carry of less than 270 yards when hit 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.

3. 2. The golf ball according to claim 1, wherein the content of the butadiene homopolymer rubber is 50% by weight to 95% by weight, where the total weight of the rubber material is 100% by weight.

4. 2. The golf ball according to claim 1, wherein the number average molecular weight of the butadiene homopolymer rubber is 50,000 g / mol to 2,000,000 g / mol.

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

6. 2. The golf ball according to claim 1, wherein the secondary rubber is devulcanized rubber.

7. 2. The golf ball of claim 1, wherein the ratio of the contact time measured in accordance with 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 in accordance with the standard TPX3009 (Rev. 2.0) jointly established by the British Golf Association and the United States Golf Association is 560.5 to 600.

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

9. 2. The golf ball of claim 1, wherein the secondary rubber is dispersed in the form of a dispersed phase within the butadiene homopolymer rubber, which is present in the form of a continuous phase.

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

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