DE9001167U1 - Multi-piece golf ball - Google Patents

Description

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Multi-piece golf ball

The present invention relates to a multi-piece golf ball, more particularly to a golf ball having a hollow, spherical shell made of a polymeric material and a unitary, non-cellular core made of a material which is in liquid at the time of introduction into the shell.

There are two types of golf balls, namely one-piece and multi-piece balls. One-piece balls consist of a core made of a polymer material into which a plurality of depressions are formed in order to improve the flight characteristics of the ball. Multi-piece balls consist of either a wound core or a one-piece core which is provided with a separate cover. The present invention relates to the latter multi-piece golf balls and to their manufacture at reduced costs while maintaining or improving their functional behavior.

More than sixty years ago, balata, a natural resin, was widely used as a golf ball cover material. When this material is used as a golf ball cover, it becomes necessary to incorporate a complex core into the golf ball. Often, the core of the golf ball is its most complex component. According to the invention, known golf ball cores are replaced by simplified, unitary cores made of inexpensive materials that are injected in their fluid state into a hollow shell. The present invention thus relates to a novel golf ball that has a hollow shell made of

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polymer* material into which the core material is injected.

Over the last twenty years , synthetic polymeric materials and their blends have been widely used as golf ball coverings. In order to maintain the performance of golf balls, whether these covers are made of natural or synthetic materials, it has been necessary to use expensive, pre-formed core systems around which the cover material is molded, complicating the manufacturing process and thus increasing manufacturing costs.

With the present invention it is possible to avoid a complicated expensive core system and still produce golf balls that have an amazingly good recovery coefficient and can be produced at reduced costs. It is also possible to adjust the inertial coefficient of the balls produced according to the invention. These advantages are achieved while at the same time it is possible to incorporate optical brighteners into the polymer shells. The present invention thus relates to golf balls including their shell materials and

their core materials. 25

Various types of golf balls and methods of manufacturing them are described in the literature. Examples include GB-PS 6566 and US-PS 46 53 752. The first publication describes a golf ball with an inner core that has a natural rubber bladder filled with gas under pressure . All of this is contained in a thick outer shell of gutta-percha. The corresponding elasticity is obviously achieved by the internally compressible inner core, which is suf «ic

elastic shell. In contrast, the golf ball of the present invention derives all or a significant portion of its elasticity from its shell. The US PS

46 53 752 relates to a softball or baseball made from a plastic shell formed from hemispheres with an injected cellular core. The resulting product is a softball whose elastic properties are similar to those of the golf ball of the present invention. are completely different. Finally, in the US PS

47 98 386 discloses a golf ball in which a pre-formed core is used, onto which a thick shell is then applied.

For the last 40-50 years or so, golf balls have been manufactured by bonding the cover to a core. The cover can be applied to the pre-formed core by molding two half-shells together, or by placing a core in an injection mold and molding the cover directly onto the previously placed core.

Golf balls have been molded using various liquid components for at least 50 years. The most common way has been to make a pre-formed bladder and fill it with a suitable liquid. These pre-formed bladders have been filled with, for example, water, mineral oil, honey, and aqueous solutions of organic and inorganic materials in the past. It is believed that after the balls were fully formed, liquids were injected into the partially filled bladders described above. For example, liquids were injected into the spaces between the various strands of the rubber-wrapped cores after a finished ball had been made.

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From the foregoing, it is clear that golf balls have been made with central regions comprising both rubber and liquid components, such as a liquid in a centrally located bladder and a liquid at the centers of the rubber wraps. However, no golf ball has yet been made with a shell whose center was initially filled with a liquid alone.

No prior art golf ball or manufacturing process teaches the inventive combination of a golf ball with a hollow, spherical shell made of a polymeric material and a uniform, non-cellular core made of a material that is a liquid at the time of introduction into the shell, so that such a golf ball can be produced particularly effectively and economically from known materials using conventional manufacturing processes.

The invention is based on the object of providing a golf ball with which the disadvantages of the prior art can be overcome and which makes a significant contribution to the development of golf balls.

Another aim of the invention is to reduce the cost of multi-piece golf balls by injecting a non-cellular liquid core material into a pre-formed shell.

The aim is also to improve golf ball shell/core designs to reduce costs.

Finally, the invention aims to maintain or improve the functional behavior of golf balls through a design that enables a reduction in material costs and a simplification of the manufacturing steps by using a preformed shell instead of a preformed core as the starting point for manufacture.

The above object is achieved by the invention as disclosed in the claims. In summary, the invention is realized by an improved golf ball having a unitary core and a shell, the shell being formed as a hollow, spherical shell of polymeric material and having a non-cellular core injected into the shell which consists of a material which is a liquid at the time of introduction into the shell.

A golf ball according ^to the invention can be manufactured by the following steps: (1) forming a pair of hollow, spherical halves from a polymer; (2) joining the halves together to form a hollow, spherical shell; (3) introducing a liquid through a hole in the shell to form a non-cellular core; and (4) sealing the hole.

The invention is explained in detail below using exemplary embodiments in conjunction with the drawing. The drawing shows:

Figure 1 is a side view, partly in section, of a first embodiment of a golf ball;

Figure 2 is a side view similar to Figure 1, but showing a different construction;

Figure 3 is a side view similar to Figure 1 showing a

shows another thin-walled shell construction;

Figure 4 is a side view similar to Figure 3, but showing a different core construction:

Figures 5 and 6 sections through fora halves for forming the

two matching halves of a golf ball cup;

Figure 7 is a sectional view of two hemispherical shell halves inserted into two opposite mountings of a rotary welding machine, before connection

to form a shell;

the figures 8, 9, and

Partial views of further implementation forums

the connecting area of the shell halves, where parts of the fastenings are also shown; 25

the figures

and 12 sectional views of shell halves of a

further execution fora before the connection;

the figures

13, 14 and

Sectional views of a golf ball shell after

the connection of the shell halves, whereby the injection of the core material

filling of the shell and formation of the core is shown;

the figures 16, 17, 18

and 19 partial sections of further execution forsss 5

of shell constructions in which the shells are designed to have certain physical properties.

Like reference numerals refer to like parts throughout the figures.

Figure 1 shows a golf ball 10 constructed in accordance with the present invention. Figure 1 is a partial sectional view with portions broken away to illustrate certain internal design features. The golf ball constructed in accordance with the present invention maintains or improves the functionality of golf balls currently known and used.

this further. Br consists of two main components, a 2O

inner section or core 12 and an outer section or a shell 14. The core is spherical, while the shell has a hollow spherical shape. The outer surface of the core is in contact with the inner surface of the shell The outer surface of the shell is provided with depressions 16 to achieve improved flight characteristics and to provide an appearance that is essentially the same as that of commercially available golf balls. The selection of a suitable depression pattern is within the scope of the expert in this field.

When describing the individual components of the golf ball, the term "spherical" is used for both the core and

L · I

also used for the shell. When referring to golf balls and their components, it will be understood by those skilled in the art that the term "spherical" also includes surfaces that have slight deviations from the perfect ideal geometric shapes, such as distortions on the outer surface of the ball to affect its aerodynamic properties. In addition, the inner surfaces of the shell and the core may contain similarly incorporated patterns.

In the embodiment of Figure 2, the core 18 consists of

a solid material instead of the liquid material of Figure 1. Figures 3 and 4 show a further embodiment of the invention with a thin-walled shell 20 and a liquid core 22 in the embodiment of Figure 3 and a solid core 24 in the embodiment of Figure 4.

According to the invention, thermoplastic materials are preferred as materials for the shell. Typical properties that are desirable for the corresponding resin, but do not represent any limitations, are good flowability, moderate stiffness, high wear resistance, high tear resistance, high elasticity and good mold release, etc.

Preferred polymeric materials for the invention are 25

ionic copolymers of ethylene and an unsaturated monocarboxylic acid, which are available under the trademark "SURLYN" from the B. I. DuPont De Nemours 6 Company, Wilmington, USA and are copolymers of ethylene and methacrylic acid, partially neutralized with zinc and sodium or lithium, and as are available under the trademark ESCOR from the Exxon Chemical Company, Houston, USA, which are copolymers of ethylene and acrylic acid, partially neutralized with zinc or sodium.

In the various embodiments of the present invention, the shell has a thickness ranging from about 1,521 mm to about 10,414 mm. Standard golf ball covers in use today have a thickness of about 2,286 mm.

According to a preferred embodiment of the Sriinäu&£ mir-S the shell is made of mixtures of ionic zinc and sodium copolymers, which are sold under the trademarks

äet ii^i-&idigr; S.I. DuPont 3>« ESfcjrs Company, Inc.

v*ii iriebeii ^. Another preferred embodiment comprises mixtures of ^o» Surlyn and "SUP^YN" 1706/9910 and 1605/8940.

Singular copolymers can also be used as shell materials in the invention. These singular materials are described in US-PS 34 54 280, üfc* Use of Surlyn resin mixtures according to the above The preferred embodiment described is explained in US Pat. No. 3,819,719. Ionic copolymers of the type which can be used in accordance with the invention are further explained in detail in US Pat. Nos. 3,264,272 and 4,679,795.

Surly &eegr; resins are ionic copolymers that contain sodium or

Zinc salts of the reaction product of an olefin with 2-8 C atoms and an unsaturated monocarboxylic acid with 3-8 C atoms. The carboxyl groups of the copolymer can be completely or partially neutralized.

The invention can also be used in connection with golf ball shells made of cellular polymeric material, as described in US-PS 42 74 637.

Other synthetic polymer materials that can be used according to the invention as shell materials include Ho-copolymers and copolymers and belong to the following groups:

^S Cl; Vinyl resins obtained by copolymerisation of vinyl chloride or by copolymerisation of vinyl chloride with vinyl acetate, acrylic esters or vinylidene chloride;

(2) Polyolefins such as polyethylene,

Polypropylene, polybutylene and copolymers, such as polyethylene naethyl acrylate, polyethylene ethyl acrylate, polyethylene vinyl acetate, Polyethylene methacrylic or polyethylene acrylic acid or polypropylene acrylic acid or terpolymers of these and acrylic esters and their metal ionomers, polypropylene/EPDM grafted with acrylic acid, as sold under the trademark "Polybond" by the company Reichhold Chemicals, Inc., Hackettstown, Mew Jersey USA, or anhydride-modified polyolefins, as sold under the trademark "Plexar" by Northern Petrochemical Company,

Rolling Meadows, Illinois, USA. 25

(3) Polyurethanes, such as those produced from polyols and diisocyanates or polyisocyanates;

(4) Polyamides, such as poly(hexaethyleneadipanide) and others made from diamines and dibasic acids, as well as those made from amino acids, such as poly(caprolactam) and mixtures of

Polyamides such as Surlyn, polyethylene, ethylene copolymers. EDPH etc·

(5) Acrylic resin mixtures of these resins »with polyvinyl chloride, blastones etc.

(6) Thermoplastic rubber, such as urethanes, olefinic thermoplastic rubber, such as mixtures of polyolefins with BPDM, block copolymers of styrene and butadiene or isoprene or ethylene-butylene rubber, poly&therblockamides, an example of such a product is sold under the trademark "Pebax" by Fir^ji Rilsan Industrial, Inc. Birdsboro, USA;

(7) Polyphenylene oxide resins or blends of polyphenylene oxide with high impact polystyrene, as sold under the trademark "Noryl" by the General Electric Company, Pittsfield, MA, USA. , _.:_,■

(8) Thermoplastic polyesters such as PET, PBT, PBTG and elastomers such as those sold under the trademark "Hytrel" by E.I. DuPont De

Nemours & Company of Wilmington, Del., USA and

"Lomod" distributed by General Electric Company. Pittsfield, MA, USA.

(9) Mixtures and alloys of polycarbonate with ABS, PBT, PET, SMA, PE, elastomers etc. and of PVC with ABS or EVA or other elastomers. Mixtures of thermoplastic rubber with polyethylene, polypropylene, polyacetal, nylon, polyesters, cellulose esters etc.

.18'

In the above description, abbreviations have been used to explain certain polymers. These abbreviations have the following meaning:

ABS Acrylonitrile Butadiene Styrene PBT Polybutylene terephthalate PBT Polyethylene terephthalate SMA Styrene Maleic Anhydride

PB Polyethylene
10

PBTG Polyethylene terephthalate/glycol-modified BDPM Ethyl propylene non-conjugated diene terpolymer PVC Polyvinyl chloride EVA Ethylene vinyl acetate

The above list is neither limiting nor exhaustive, but merely represents the broad range of polymeric materials that can be used to manufacture the shell according to the invention. Bs

Mixtures of the above-mentioned materials can also be used. In addition, the polymers used to produce the outer shell can also be stress-oriented after the shell has been produced.

Polymeric materials reinforced in the shell according to the invention 25

be used.

It is within the scope of the invention that materials can be added to the shell materials that do not affect the basic novel properties of the corresponding composition. Such materials are, for example, antioxidants, antistatic agents and stabilizers.

As is clear from the above description, the invention can be used in conjunction with a wide variety of poly-

.19

■Other materials that are suitable for forming the shells are used.

The white base color of the shell of the golf ball is achieved by pigmenting one of the polymeric materials mentioned above. Suitable pigments for use according to the invention are, for example, the following: titanium dioxide, zinc oxide, zinc sulfide and barium sulfate.

The amount of pigment used in the polymeric material for the shell will, of course, depend on the particular polymeric material and the particular pigment used. The concentration of pigment in the shell material can range from about 1% to about 25% based on the weight of the polymeric material. riales. My preferred range is about 1\ to about 5% based on the weight of the polymeric material. The most preferred range is between about 1% and about 3% based on the weight of the polymeric material. The percentage of pigment used will be largely by the weight needed to give a golf ball the preferred physical properties. Those skilled in the art will understand that the percentage of pigment added must be balanced with the weight of the core material to achieve the desired density of the resulting

golf ball. Preferred shell materials are the ionomers described above, including Surlyn and BSCOR resins, which can be used in conjunction with fillers, pigments and other additives may be used. The most preferred pigment, if such is to be used, is titanium dioxide. When this combination of components is used, the concentration of titanium dioxide in the shell material should range from about 1% to about 10%, based on the weight of Surlyn resin used. A particular

.20,

The preferred range for the concentration of titanium dioxide is about 1% to about 5% based on the Surlyn resin used. A particularly preferred concentration for the titanium dioxide is 2% based on the

Weight of the Surlyn resin used.

As has been extensively described above, the invention can be practiced with a wide variety of polymers. However, in the pigmented state, many of these polymers, particularly the Surlyn resins, are not glossy after injection molding. However, experience has shown that the average golfer prefers a glossy golf ball. To produce glossy golf balls, the balls of the invention can be molded with a clear Epoxy urethane topcoat system. This system consists of a clear epoxy primer and/or water borne primer followed by a clear urethane coat. However, the use of the clear topcoat system is not essential to the desirable results of the invention. However, such a system is particularly desirable. In addition to a high initial gloss, the above-mentioned system results in a golf ball that is durable and

It is understood that the 25

Expert that other clear transfer systems can also be used.

It is further understood that the golf balls constructed according to the invention can be provided with a pigment color in a conventional manner.

The radius of inertia is an important characteristic of a golf ball. Br is generally used as a way of handling rotational forces when the ball is spinning

In a golf ball constructed according to the invention, the radius of inertia can be varied in a simple manner by increasing or decreasing the density of the outer shell and/or the density of the inner core. For example, if one wants to create a golf ball in which the radius of inertia is located near the outer circumference of the ball, then ^one can incorporate heavy material into the outer shell of the golf ball according to the invention, which does not affect the playing properties of the ball, but creates mass in the outer shell. For example, the outer shells can contain small amounts of heavy metal salts, such as a tungsten salt or a lead salt. Similarly, the outer shell can also contain powdered metals. With other methods, the distribution of mass along the radius of the ball can be changed, while »either the density of the core material or the density of the material for the outer shell is changed.

The specific gravity of the shell described above is between about 0.75 and about 1.25, preferably 0.97. Standard golf balls have an average specific gravity of 1.13, a diameter of

at least 42.67 mm and a weight of less than 45.926 g 25

To provide a golf ball having physical and functional properties similar to a standard golf ball, the core is preferably made of a material having a specific gravity greater than that of the ball and the cover. In the present invention, the core may have a diameter of between about 21.84 mm and about 36.42 mm, preferably 33.02 mm. The core filled with core material may have a specific gravity of between about 0.8 and about 3.9, preferably about 1.32.

understands itself for • •
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of the nucleus depending on the physical dimensions and density of the outer shell and the

Diameter of the finished golf ball must be changed.

It is understood that a wide variety of materials can be used, including oils, gels, hot melts and liquid materials. Hot melts are materials that

at or about normal ravusteaperatur fixed s1a<3 at IO

However, they become liquid at elevated temperatures. This property allows for easy injection into the shell to form the core. Examples of suitable gels are water-gelatin gels, hydrogels and water/methylcellulose gels. Gels. Embodiments of pads with a gel core or other solid core are shown in Figures 2 and 4. Examples of suitable melts include waxes and bite melts. Examples of suitable liquids, as shown in Figures 1 and 3, include either solvents solutions such as glycol/water, salt in water or oils or colloidal suspensions such as clay, barite, carbon black in water or other liquids or salt in water/glycol mixtures. The preferred material is the liquid solution described above. An example of a suitable core material is a solution of an inorganic salt in a mixture of water and glycol. The inorganic salt is preferably calcium chloride and the glycol is glycerin.

In the thicker-walled embodiments (about 10.41 mm to about 4.06 mm), the shell material provides almost all or most of the elasticity required for the proper functioning of the golf ball constructed in accordance with the invention. In the thinner-walled

.23

In embodiments (about 1.52 mm to about 4.06 µm), the ball functions and behaves in a conventional manner, deriving elasticity from the core material and the shell. The shell may also range in thickness from about 1.52 mm to 10.43 mm, preferably have a thickness of about 1.91 µm to 7.62 µm, and most preferably have a thickness of about 2.29 µm to 4.83 µm. It is understood that properties of the shell material and thickness are interrelated. These two variables must be balanced to provide optimum performance.

liquid SSateriöi, -33IS erf indusg^eslg into the shell

is formed in the core»> can be formed by reactive liquid systems which in combination Examples of suitable reactive liquids are silicate gels, agar gels, peroxide-cured polyester resins, two-part epoxy resin systems and peroxide-cured liquid polybutadiene rubber compositions. It is understood that other

r«*xtive liquid systems can be used, depending on the physical properties of the cover and the desired physical properties of the finished golf ball.

regardless of whether it is a liquid or a Since it is a solid, the nucleus is composed of a uniform common material over its entire extent. The outer surface of the nucleus is in contact with the inner surface of its shell. All nuclei are also essentially homogeneous throughout their mass.

In the preferred manufacturing process for the golf balls described above, two hemispherical shell halves 28 and 30 are formed, preferably by injection molding,

11 · ·

before they are connected to each other to form the complete shell . Figures 5 and 6 show fora halves 34 and 36 with holes 38 and 40 for the introduction of the

The material is liquid fora from which the shell is to be made . The two halves of the fora are of identical shape , except for their equator, where they meet one another. ■-' should be connected. Such ic «ialften can also

^: i be completely identical and have flat planar surfaces 42 and

44 at the equator of the sphere in the connecting areas -A- sen, as shown in Figure 8. However, it is preferred that

'; Tongue and groove configurations 46, 48 are provided to assist in the correct arrangement of the halves relative to each other. This is shown in Figures 1 and 2 and Figures 5, 6 and 7 and 13, 14 and 15. Other Embodiments at the equator of the sphere are used, for example matching waves 50 and 52 of protruding and recessed segments across the shell thickness, as shown in Figure 9. In the embodiment of the thin-walled shell of Figures 3, 4 and 10, the

Dividing line 54 and 56 the fora of a cylinder and the circumference

of the sphere, whereby this dividing line is oriented at an angle to the equator of the sphere. This creates a triangular projection in the lower shell.

half and a matching triangular recess in 25

the upper half of the shell. This provides additional Surface is provided for the connection. During rotation welding, the centrifugal forces acting on the shell edges and the tool walls press the matching halves against each other, so that a particularly good connection is achieved.

Figures 11 and 12 show a preferred tongue and groove arrangement, wherein the length H-1 of the tongue is slightly less than the length H-2 of the inner wall of the groove,

'2 5

but slightly larger than the length H-3 of the outer wall of the groove.

Other methods of manufacturing the shell include conventional blow molding, injection blow molding and spin casting.

The recesses 16 on the outer surface of the shell aids are shown as if they were formed during injection molding of the

Helps forest murder *lr*D _: ?■ understands me i^doeh. that

In certain designs, the ball has a smooth IO

outer surface can be formed and the recesses are recessed after the halves have been joined together during the manufacturing process, either before or after the core is injected and the hole plugged. The temperature for forming the recesses must be sufficiently low so as not to have a detrimental effect on the core.

The halves are joined together using one of a variety of methods. The preferred method is to spin weld the halves, with one of the halves 30 being fixed in a stationary fixture unit 60, shown as the lower half in Figure 7.

and the other half 28, shown as upper half, in a 25

Fastening unit 58 is stored, which quickly over a

Vertically sense is rotated while it is moved in the axial direction a.f towards the fixed half, as indicated by the arrows in Figure 7. The movement of one half relative to the other half while both halves brought into contact with each other, generates sufficient heat to cause a final cohesive bond between the melting and coalescing thermoplastic materials of the halves. A single, unified

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Hollow sphere which forms the shell of the ball. Such a rotation welding method is common in the art and is described, for example, in US Pat. No. 2,956,611. A commercially available rotation welding machine with which such a process can be carried out is Model No. SPW-I-BC from the Olsen Manufacturing Company of Royal Oak, Michigan, USA. Other joining techniques can also be used to couple the halves. Such other techniques include ultrasonic welding, vibration welding, laser welding, solution welding, etc.

medium welding, compression molding or even gluing »it help a suitable adhesive that has properties that are adapted to the properties of the shell halves.

Next, in the manufacturing processes for the preferred embodiment, a hole 64 is made in the shell 14, such as by drilling. The hole can also be made during molding. Bs preferably tapers radially inward toward the center of the ball to facilitate its subsequent closure. It is understood that one or more holes of the same or different size can be drilled or made in order to allow the liquid core material to enter the outer shell. The material is then

of the core 12 is injected through the hole into the middle of the shell, for example via a hypodermic needle 66 etc., in order to completely fill the middle of the shell to form the core. By plugging the hole, one The manufacturing process is completed by the conical plug 68 and the machining of its cylindrical extension, whereby of course the recesses are still provided according to the manufacturing process described above. The material of the plug is preferably the same as that of the rest of the shell 14. The plug is placed in the hole.

strengthens, by sealing the shell using one of the methods described above, with spin welding currently being preferred. In certain embodiments, mfcn can leave the sealing of the hole to the core material. 5

In another embodiment of the invention, the shell and core are formed by any of the processes described above. However, the shell 72 of Figure 16 is formed from a first or inner layer 74 having a thickness slightly less than that of the finished ball. Such a shell forms an inner layer of the finished composite shell or laminate consisting of multiple layers. The final outer layer 76 is preferably applied to the outer surface of the inner layer 74 by conventional injection molding or by centrifugal molding. After the outer layer 76 of the shell has been formed, the recesses 16 are formed in the outer surface of the ball. These recesses can also be formed during molding by using appropriately shaped mold segments.

By forming the shell as a multi-layer laminate,

whose materials are selected so that the functional 25

behavior of the ball is adapted to a very specific application. For example, properties such as color, friction behavior, durability and resistance to wear and carving can be incorporated into the outer layer. The inner layer can simply provide the desired elasticity. Furthermore, the inner layer can have a relatively high elastic modulus to ensure increased durability and flexibility, while the outer layer can have a lower elastic modulus to ensure more ariler frictional contact with the

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The outer layer can only be given a shine up to a maximum of 10 mm, so that the use of such brighteners is kept to a minimum. 5

This design of the shell, which is made of a large number of interconnected layers, can be manufactured using a conventional pendulum process. In this»

Vereinifen Forira uic lüüele Rückschicht first, in the Forum IO

injected. Then the outer layer, made of a different material than the inner layer, is injected over the first layer or vice versa. This is achieved by successive injections into a common fora over a fora component when making the shell halves in a layered build-up. This molding technique is common in the molding of typewriter keys, where the different injected materials form the visible letters.

Figures 17, 18 and 19 show three further embodiments of the invention, among others to be able to adapt the shell properties to a specific application. Although these three different embodiments are adapted to a specific

Core are shown, the execution forums of the 25

Figures 17, 18, 19 and 16 can be used in a corresponding manner in the manufacture of a hollow shell or a half- ^spherical fora.

Figure 17 shows a further embodiment of the invention. In this embodiment, the shell 78 has a middle cellular layer 90 which is embedded between two non-cellular skins 92 and 94. The non-cellular skins 92 and 94 are formed in situ by changing

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the process parameters with which the shell 88 is formed.

The skins 92 and 94 can be modified and formed by a variety of methods. For example, they can be molded by changing the temperature of the mold during the initial stages of the injection molding process and by changing other parameters such as melt temperatures, injection time, injection speed, injection pressure, nozzle type, gate placement, venting, holding pressure, holding time, batch weight, blowing agent concentration, nucleator concentration, polymer composition, mold surface treatment and mold lubricant. More details are described in U.S. Patent No. 4,277,637.

Figure 18 shows a further embodiment of the invention, in which the shell 98 has a substantially uniform cellular structure. In this embodiment, the shell 98 is formed over a hemispherical molding aid.

Figure 19 shows a further embodiment of the invention. A shell 102 has a middle layer 104,

which is embedded between two layers 106 and 108. The 25

middle layer 104 has an apparent density, which is less than that of the other layers. In other words, the other two layers have a greater apparent density than the middle layer. It will be understood by those skilled in the art that the apparent density of the covering will naturally vary in the area of the interfaces between the layers. These respective densities of the layers can be changed by changing the process parameters in the manner described above.

.30

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For the purposes of this description, when we speak of "density test "specific gravities", we refer to them as "apparent densities" and "apparent specific gravities". This is to express

^ä SiEtOf^. &aacgr;&agr;$ some of the covers designed according to the invention are not uniform, as they may have skin &xgr; and variable cell structures. The terms used above take these variable

Färaaei - and gave £j.a actual density and the tat-IO

specific court of average structures.

The corresponding terms also refer to the density and specific gravity of the liquid materials injected into the shell to form the core.

The materials for the shell and/or the core of the golf ball constructed according to the invention can also be used as a means for changing or regulating the recovery coefficient (Coefficient of Restitution) can be used. The coefficient of elastic recovery of a golf ball generally indicates the elasticity of the ball and thus indicates the distance

the distance the ball travels when it is hit by a golf club-25

ger has been beaten. The provision coefficient is normally sat while Ban hits a finished golf ball at a fixed speed against a hard surface. After the ball has bounced off the surface, its speed is measured again. The ratio between the rebound speed and the impact speed then forms the recovery coefficient. This recovery coefficient relates directly to the elasticity of a golf ball and indicates how far it moves,

when «r is hit by a golf club «order if all other variables are constant.

The elasticity of a golf ball is regulated by the United States Golf Association through a test commonly referred to as the initial velocity test. In the test, a golf ball is struck by a rotating mass, the rotating mass moving at a rate of about 30.4 seconds per second. After each strike, _the speed of the ball is measured as it travels two

Iiicbt»chir»e p&seie-t, which are arranged ~or the club face

■sir?<*. The axial deflection limit for a golf ball tested in this manner is 77.72 m per second at 24°C. This limit of 77.72 m per second corresponds to an average coefficient of rebound of about 0.815, given an impact velocity of 38.10 m per second.

Li- The recovery coefficient data given below were obtained when »balls from a pneumatic gun« with a muzzle velocity of 38.10 ■ per second were fired against a steel plate placed 3.05 ■ from the muzzle of the gun, and indeat nan both the

Initial speed as well as return speed 25

of the rebounded ball. The relationship between the Rebound speed to the initial speed is the special recovery coefficient.

EXAMPLE 1

Using the procedures described above, golf balls were manufactured as follows:

.32

Formulation 514-92-1 was injection molded into half-shells that had a diameter of approximately 42.672 mm and a thickness of approximately 4.826 mm. Formulation 514-92-1 had the following composition:

Parts by weight

«&bull;irlyn 1605/8940 tit ALYN is a trademark of S.I. DuPont De Nemours 6 Company,

Wilmington, Delaware, USA) IO

Surlynn 1706/9910

Unitane 0-110 Titanium dioxide 2.35

(Unitane 0-110 is a trademark of

Kemira, Inc., Savannali, Georgia, USA)

Uvitex OB 0.10

(Unitex OB is a trademark of Ciba-Geigy, Hawthorne, New York, USA)

Ultramarine blue 0.024

(Ultramarine blue is produced by the company

Whittaker-Clark and Daniels, South 25

Plainfield, New Jersey, USA)

Total 102,474

The pole height was about 0.1778 mm larger than the

Equator radius, so that material could flow during the rotational welding of the two half shells to form the hollow sphere. The two shells had a tongue and groove configuration. They were welded at 4.100 rpm and 15 seconds.

welded together to form a hollow sphere. The hemisphere with the groove had a molded conical hole with a diameter of 3.175 mm on the sweeter sphere surface and a diameter of 1.588 mm on the inner spherical surface.

The specific gravity of the cover material can range from 0.956 to 1.25. The preferred range is 0.97 to 1.0.

The flexural modulus at 23· C was in the range of 2067 to

4134 bar. The preferred range was 3100 to 4134 bar. The flexural modulus was determined according to ASTM Test &eegr; 790.

The samples prepared using ionomer compounds had the following average data:

Specific gravity: 0.97 Actual flexural modulus: 3445 bar Cover weight: 21 g

The estimated volume of the cover was 16.04 cm·.

The following formulation A was introduced as a liquid core material using a hypodermic syringe, completely filling the interior. Formulation A had the following composition:

Formulation A Parts by weight Calcium chloride 45 Water 45 Glycerine 10

Total 100

.3.4

A molded plug, having the shape shown in Figures 12 and 15 and made of the same material as the bowl, was spin welded to the hole to seal the contents. The welding conditions were 3150

rpm and 15 see. residence time.

After deburring, the final product had the following average properties:

Average diameter: 43.027 mm 10

Average weight: 45.9 g

Average PGA compression: 104 Average recovery coefficient: 0.747 15

These results represent the average of the three balls with the highest coefficients out of six balls produced.

The test was repeated in the manner described. Only 12 balls were produced.

Average diameter: 42.799 mm Average weight: 45.4 g

Average PGA Compression: 99 Average Reset

Coefficient: C,725 EXAMPLE 2

The procedure according to Example 1 was repeated, except that glycerin was used as the filler.

I I · ·

&bull; f *

&bull; f

.&bull;35

&igr;&igr; ill

After deburring, the resulting product had the following properties:

Average diameter: 43.002 mm Average weight: 44.4 g

Average PGA Compression: 107 Average Reset

coefficient: 0.758

These results represent the average of the three BSlIe Bit IO

the highest coefficient of four balls produced.

For example 1, 12 additional balls were made.

Average diameter: 42.824 mm Average weight: 43.8 g Average PGA compression: 99 Average recovery coefficient: 0.732

BKlSFIgL 3

The procedure according to Example 1 was repeated, with the

Exception: hydraulic oil Mobil Etna 26 25 is used as filler material

was used (trademark of Mobil Oil Corp., New

York City, Hudson, USA).

After deburring, the resulting product had the following properties:

Average diameter: 43.002 Average weight: 37.5 g

Average PGA compression: 108

.&bull;36

Average recovery coefficient: 0.749

These results represent the average of the three bales ■with the highest coefficients on the four bales produced.

According to Example 1, the tests of Example 3 were repeated, and ·« 12 BSlIe were produced. After deburring, the resulting products have the following properties* IO

Average diameter: 42.748 mn Average weight: 37.1 g Average PGA compression: 99 Average recovery coefficient: 0.745

EXAMPLE 4

The procedure of Example 1 was repeated, with the exception that gelatin/sugar, Sssssr&mdash; solution, formulation B, was used as the filler. Formulation B had the following composition:

Formulation B Parts by weight

Gelatin 45

Royal Gelatin Desert., manufactured by Nabisco Brands, Ine. , SO Bast Hanover N.J. 07936, USA

Sugar 80

Water 240

Total 365

&bull;I · · It ·· · r a·

&bull;&igr; J I &igr; · ti··

&bull; < · · . I · · I,.· · ti· II· It·

The formulation was introduced at 66°C. Upon cooling, a solid gel was formed.

After deburring, the resulting product had the following properties: 5

Average diameter: 42.8SO ma Average weight: 42.7 g Average PGA compression: 106 Average recovery coefficient: 0.749

These results represent the average of the bales plus the three highest coefficients from four bales produced.

As described above in connection with Example 1, the tests were repeated and 12 bales were produced. After deburring, the resulting products had

the following properties: 20

Average diameter: 42.774 ma Average weight: 42 g

Average PGA compression: 98

Average reset-25

coefficient: 0.733

EXAMPLE S The procedure of Example 1 was repeated, with the

Exception: The formulation 514-93-3 was used as the shell material, which had the following composition:

IO

I .. lilt i · · · * t · t * »

Parts by weight

Escor 900 50 (Escor is a trademark of Exxon Chemical, Houston, Texas, USA)

Escor 4000 50

ürit&ae 0-110 Tikns-äoxid 2,35

Uvitex OB 0.10

Ultramarine Blue 0.024

Total 102,474

After deburring, the resulting product had the following properties:

Average diameter: 43.002 mn Average weight: 45.9 g Average PGA compression: 104 Average recovery coefficient: 0.747

20

These results represent the average of the three bales with the highest coefficients out of four bales produced,

As described above in Example 1, the tests were performed 25

Example 1 was repeated and 12 golf balls were produced. After deburring, the resulting products had the following physical properties:

Average diameter: 42.850 mm Average weight: 45.4 g Average PGA compression: 104 Average recovery coefficient: 0.738

Claims (34)

Treasury claims 1. Golf ball characterized by a hollow spherical shell (14) of polymeric material and a unitary core (12) of a material which is, at the time of injection into the liquid, or is capable of being handled as a liquid . 2. 3olfbali according to claim 1, characterized in that the material of the shell (14) has a thickness between about 1.5?4 mm and about 10.414 mm. 3. Golf ball according to claim 1, characterized in that the material of the shell (14) has a thickness between about 1.905 mm and about 7.620 mm. 4. Golf ball according to claim 1, characterized in that the material of the shell (14) has a thickness between about 2.286 mm and about 4.826 mm. 5. Golf ball according to one of the preceding claims, characterized in that the shell (14) is formed from a polymeric material selected from the following group: polyurethane resins, polyolefin resins, ionic copolymers, which are metal salts of the reaction product of an olefin with 3-8 C atoms and an unsaturated monocarbon &bull; ■ I · * &bull; ■ « acid with 2-8 C atoms, as well as mixtures of these polymers. 6. Golf ball according to one of claims 1 to 4, characterized in that the shell *14) is formed from an element selected from the group consisting of ionic copolymers De, which are the sodium salt of the reaction product of an olefin with 2-8 C atoms and an unsaturated monocarboxylic acid with 3-8 C atoms and the zinc salt of the reaction product of an olefin with 2-8 C atoms and an unsaturated monocarboxylic acid with 3-8 C atoms. 7. Golf ball according to one of claims 1 to 4, characterized in that the shell (14) is formed from a mixture of ionic copolymers selected from the group consisting of ionic copolymers which are the sodium salt of the reaction product of an olefin with 2-8 carbon atoms and an unsaturated monocarboxylic acid with 3-8 carbon atoms and the zinc salt of the reaction product of an olefin with 2-8 carbon atoms and an unsaturated monocarboxylic acid with 3-8 carbon atoms. 8. Golf ball according to claim 1, characterized in that the shell (14) is filled with a material selected from the group consisting of a liquid, a gel or a melt. 9. Golf ball according to claim 2, characterized in that the shell (1.4) is filled with a material selected from the group consisting of a liquid, a gel or a melt. 10. Golf ball according to claim 3, characterized in that (He shell (14) is filled with a material selected from the group consisting of a liquid, a gel or a melt. 11. Golf ball according to claim 4, characterized in that the shell (14) is filled with a material selected from the group consisting of a liquid, a gel or a melt. 12. Golf ball according to claim 5, characterized in that the shell (14) is filled with a material selected from the group consisting of a liquid, a gel or a melt. 13. Golf ball according to claim 6, characterized in that the shell (14) is filled with a material selected from the group consisting of a liquid, a gel or a melt. 14. Golf ball according to claim 7, characterized in that the shell (14) is filled with a material selected from the group consisting of a liquid, a gel or a melt. 15. Golf ball according to claim 1, characterized in that the shell consists of a deformable polymeric material. 16. Golf ball according to claim 15, characterized in that the shell is formed from two substantially hemispherically shaped halves, and that these halves are spin-welded, ultrasonically welded, solvent-welded, compression-molded or glued together. 17. Golf ball according to claim 16, characterized in that one or more holes are drilled or formed through the shell for filling the shell and the hole or holes are plugged after injection. 18. Golf ball according to claim 8, characterized in that the polymeric material of the shell (14) is cellular. 19. Golf ball according to claim 9, characterized in that the polymeric material of the shell (14) is cellular. 20. Golf ball according to claim 10, characterized in that the polymeric material of the shell (14) is cellular. 21. Golf ball according to claim 11, characterized in that the polymeric material of the shell (14) is cellular. 22. Golf ball according to claim 12, characterized in that the polymeric material of the shell (14) is cellular. 23. Golf ball according to claim 13, characterized in that the polymeric material of the shell (14) is cellular. 2<i. Golf ball according to claim 14, characterized in that the polymeric material of the shell (14) is cellular. 25. Golf ball according to claim 8, characterized in that the polymeric material of the shell (78) comprises several layers (90, 92, 94). 26. Golf ball according to claim 9, characterized in that the polymeric material of the shell (78) comprises several layers (90, 92, 94). 27. Golf ball according to claim 10, characterized in that the polymeric material of the shell (78) comprises several layers (90, 92, 94). 28. Golf ball according to claim 11, characterized in that the polymeric material of the shell (78) comprises several layers (90, 92, 94). 29. Golf ball according to claim 12, characterized in that the polymeric material of the shell (78) comprises several layers (90, 92, 94). 30. Golf ball according to claim 13, characterized in that the polymeric material of the shell (78) comprises several layers (90, 92, 94)* 31. Golf ball according to claim 14, characterized in that the polymeric material of the shell (78) comprises several layers (90, 92, 94). 32. A golf ball according to claim 1, characterized in that the hollow spherical shell (14) is formed from hemispheres which are spin welded together adjacent their equator across an interface of tongue and groove configuration, the shell being formed from a polymeric material having a thickness of about 2.286 mm, the core (12) being non-cellular, uniform, substantially homogeneous and of a liquid material; and a plug (68) filling a hole in the shell (14) through which the liquid material has been introduced. 33. Golf ball according to claim 30, characterized in that the shell (14) is formed from a mixture of ionic copolymers selected from the group consisting of ionic copolymers which are the sodium salt of the reaction product of an olefin having 2-8 carbon atoms and an unsaturated monocarboxylic acid having 3-8 carbon atoms and the zinc salt of the reaction product of an olefin having 2-8 carbon atoms and an unsaturated monocarboxylic acid having 3-8 carbon atoms. 34. Golf ball according to claim 31, characterized in that the core (12) is a solution of calcium chloride, water and glycerine.