This invention was not made as part of a federally sponsored research or development project.
The present disclosure relates generally to grips and, more particularly, to hand grips for sporting implements.
There are many different types of grips used today for a wide variety of items, including without limitation, golf clubs, tools (hammer handles, screwdrivers, etc.), racquets (racquet ball, squash, badminton, or tennis racquets), bats (baseball or softball), pool cues, umbrellas, fishing rods, etc. While particular reference for this disclosure is being made to the application of golf club grips, it should be immediately apparent that the present disclosure is applicable to other grips as well.
Slip-on golf club grips made of a molded rubber material or synthetic polymeric materials are well known and widely used in the golf industry. The term “slip-on” as employed herein refers to a grip that slides on to a shaft or handle and is secured by way of an adhesive, tape, or the like. Slip-on grips are available in many designs, shapes, and forms.
Golf club grips historically have been made of a wide variety of materials such as leather wrapped directly on the handle or leather wrapped on sleeves or underlistings that are slipped on to the handle, or more recently rubber, polyurethane or other synthetic materials are used. Up until now, various construction methods have been used to produce a lower overall material density. Most commonly, an inner structure is formed using a light weight foam material, often EVA foam. Over this structure, a gripping layer is located and held in place through the use of either an adhesive or some other bonding method. Most commonly, this gripping layer is made from a felt material where the outside is coated in polyurethane to provide a smoother and more durable outer layer. Another existing method of manufacturing a lightweight structure to form a grip is to use expanded foam/sponge material tubes (EVA, nitrile rubber, etc.) molded, or ground, to shape. These foam/sponges also have relatively low abrasion and UV resistance, tend to wear out more quickly than traditional rubber grips, and may take on a permanent compression set over time leaving permanent depressions in the golf grip, thereby risking a potential violation of the rules of golf.
There is a trend in golf toward lighter weight. Swing grips, as used on clubs such as woods and irons, that are light weight offer the golfer enhanced performance by generally facilitating a faster club head speed. Further, there is a trend in non-swing grips, or putter grips, to oversized grips that provide a more stable grip and help prevent the wrists from becoming too active during a putting stroke. While the size of such grips increases, it is desirable to maintain the weight of the grip consistent with non-oversized grips so the balance and swing weight of the putter is maintained.
It is also desirable to offer golf grips in multiple colors. A multiple color grip is more attractive and gives the brand an identity for instant brand recognition. When molding a golf grip in multiple colors it is desirable to form a defined border between the colors that is consistent in location and shape. The defined border may be a straight line, an angled line, a curved line, or any desired geometry. The defined border between colors increases the perceived product quality and brand identity. However, this is difficult to achieve such a defined border with light weight rubber molding because the materials are not stable at the lower densities needed to achieve the desired grip weight.
It is desirable to produce lightweight multicolor compression molded grips using rubber compounds. Rubber has a good feel and is preferred by golfers. However, rubber is a heavy material with a density of approximately 1.2 g/cc. In order to reduce the density, lightweight materials must be added to the rubber compound, which further increase the difficulty of achieving a defined border. Thus, there still exists a need for a lightweight multicolor compression molded grip having a sharply defined interface between the colors, particularly one that is soft, resilient, and resistant to permanent deformation and the associated risks.
A lightweight compression molded multicolor golf grip having at least a first section and a second section of differing colors and composed of elastomer compounds having a density of less than 0.90 g/cc, and joined by cross-linking across a sharply defined cross-color interface having an interface transition zone beyond which there is no mixing of the colors. The grip has a soft feel and unique compression characteristics achieved in some embodiments through the controlled use of an expanding blowing agent in a rubber compound including an EPDM mixture. Achieving the sharply defined cross-color interface is due in part to the use of complementary geometries at opposing interface edges to increase the stability of the interface and reduce the flow during molding associated with the increased viscosity of low density rubber compounds, promote cross-linking of the sections, and better distribute and control the consolidation pressure. Traditionally compression molded elastomer compound grips feel hard or firm, which is undesirable in some grips, such as a putter grip. The best feedback for a golfer regarding grip pressure is to provide a grip with a relatively consistent and a relatively flat compressive force to compression depth line so that a golfer's grip never gets to the point of strongly squeezing the grip without sensing additional deflection. Likewise, consistency of a ratio of the compressive force to the compression depth throughout a range of compression depths, while still providing the necessary resiliency, provides improved feedback.
Without limiting the scope of the present invention as claimed below and referring now to the drawings and figures:
These drawings are provided to assist in the understanding of the exemplary embodiments of the invention as described in more detail below and should not be construed as unduly limiting the invention. In particular, the relative spacing, positioning, sizing and dimensions of the various elements illustrated in the drawings are not drawn to scale and may have been exaggerated, reduced or otherwise modified for the purpose of improved clarity. Those of ordinary skill in the art will also appreciate that a range of alternative configurations have been omitted simply to improve the clarity and reduce the number of drawings.
The present invention enables a significant advance in the state of the art. The preferred embodiments of the invention accomplish this by new and novel arrangements of elements, materials, and methods that are configured in unique and novel ways and which demonstrate previously unavailable but preferred and desirable capabilities. The description set forth below in connection with the drawings is intended merely as a description of the presently preferred embodiments of the invention, and is not intended to represent the only form in which the present invention may be constructed or utilized. The description sets forth the designs, materials, functions, means, and methods of implementing the invention in connection with the illustrated embodiments. It is to be understood, however, that the same or equivalent functions, features, and material properties may be accomplished by different embodiments that are also intended to be encompassed within the spirit and scope of the invention. The present disclosure is described with reference to the accompanying drawings with preferred embodiments illustrated and described. The disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Like numbers refer to like elements throughout the disclosure and the drawings. In the figures, the thickness of certain lines, layers, components, elements or features may be exaggerated for clarity. Broken lines illustrate optional features or operations unless specified otherwise. All publications, patent applications, patents, and other references mentioned herein are incorporated herein by reference in their entireties. Even though the embodiments of this disclosure are particularly suited as golf club grips and reference is made specifically thereto, it should be immediately apparent that embodiments of the present disclosure are applicable to other grips for implements other than golf clubs.
Referring to
The golf grip (10) is composed of at least two compression molded sections of differing color, namely a first section (300) and a second section (400) joined along a cross-color interface (500), to produce an overall density of the golf grip (10) that is less than 0.90 g/cc. The first section (300) and second section (400) may be configured adjacent to one another in any number of manners including, but not limited to, transversely dividing the golf grip (10), as seen in
The first section (300) and second section (400) are formed of elastomer compounds, or long-chain polymers, which are capable of cross-linking, which is referred to as vulcanization, across the cross-color interface (500) during compression molding. The vulcanization process cross-links the polymer chains via chemical bonds creating the elastic properties. Elastomer compounds are typically described by type or family based on the base polymer used in the formulation. The first and second sections (300, 400) may be formed of compounds including acrylonitrile-butadiene rubber, hydrogenated acrylonitrilebutadiene rubber, ethylene propylene diene rubber, fluorocarbon rubber, chloroprene rubber, silicone rubber, fluorosilicone rubber, polyacrylate rubber, ethylene acrylic rubber, styrene-butadiene rubber, polyester urethane/polyether urethane, and/or natural rubber, and combinations thereof. In one embodiment the first and second sections (300, 400) are rubber compounds of either ethylene propylene diene monomer (EPDM) or a natural rubber and EPDM mixture. In one embodiment the first and second sections (300, 400) have a high ethylene content, a high molecular weight, and a very high diene ratio EPDM for cross-linking.
In order to produce an overall density of the golf grip (10) that is less than 0.90 g/cc, in one embodiment a compression molding process is used; in part because generally injection molding of rubber based compounds cannot achieve densities less than 0.96 g/cc. With compression molding, a blowing agent is mixed into the elastomer compound and is calendered into a sheet of a desired thickness. For example, the schematic process of
As seen in
Achieving a sharply defined cross-color interface (500) along the intersection of the differing colors of the first section (300) and the second section (400) is difficult, particularly when the density of each preform is less than 0.90 g/cc to achieve an overall golf grip (10) density of less than 0.90 g/cc, which is further compounded in oversized embodiments of the golf grip (10) having an asymmetric transverse cross-section (i.e. one not having a round cross-section), which may also be contoured along the length in further embodiments, as seen in
One embodiment incorporates expanding blowing agent for expanding the compositions, which may include, but are not limited to, dinitrosopentamethylenetetramine (DPT), azodicarbonamide (AZC), p-toluenesulfonyl hydrazide (TSH), 4,4′-oxybisbenzenesulfonyl hydrazide (OBSH), and the like, and inorganic foaming agents, such as sodium hydrogen carbonate. Further, the blowing agent may include di-azo compounds which release N2 gas at high temperature, N2 gas introduced during the foaming process, CO2 from decompose chemical foaming agents, and/or expand-cell system having core-shells containing vaporization liquid inside, often referred to as expandable microspheres or microcapsules. The quantity of blowing agent is measure in parts per hundred rubber (phr).
The primary reason that compression molding is able to achieve a lighter weight than injection molding is because the quantity of blowing agent within the preforms may be higher in a compression molding process compared to an injection molding process because the blowing agent, particularly when in expanding blowing agent form, is not damaged during the compression molding process, unlike injection molding. However, expanding blowing agents introduce new complications to the compression molding process that make it difficult to achieve a sharply defined cross-color interface (500); namely, expanding blowing agents reduce the shear in the elastomer compound and lower the viscosity. This is because expanding blowing agents generally have a low friction surface. A lower viscosity elastomer compound is difficult to compression mold because the preforms may shift during the molding process due to the reduced viscosity and/or the expansion caused by the expanding blowing agent, and the interface between the sections (300, 400) may be compromised, structurally and/or aesthetically, by high quantities of expanding blowing agent causing increased instability at the interface. All of these difficulties are further heightened when producing a soft low-density multicolor compression molded grip, particularly when it is an oversized grip with may have an asymmetric cross-section, as well as significant variations in thickness.
As used herein the term sharply defined cross-color interface (500) refers to the location on the golf grip (10), after complete cross-linking during molding, at which opposing color interface edges, such as 336 and 436 or 346 and 446, of differing color preforms are originally abutted. An interface transition zone (510) is the region that is within 0.150 inch on either side of these interface edges, as seen in
An additional embodiment further improves the consistency of the cross-color interface (500) via the use of a mold that imparts a transition zone depth (530) within the interface transition zone (510), as seen in
Another embodiment improves the consistency of the cross-color interface (500) by increasing the contact area of abutting preforms opposing color interface edges, such as 336 and 436 or 346 and 446, to increase the stability of the interface and reduce the flow during molding associated with increased viscosity, as well as better distribute the consolidation pressure associated with expanding blowing agent embodiments. In order to quantify this increased contact area one must first establish a baseline contact area for comparison. The baseline contact area will first be defined for two scenarios, namely (a) where the first section (300) and second section (400) are configured adjacent to one another to transversely divide the golf grip (10), as seen in
Now, in the embodiment of
Still further embodiments improve the consistency of the cross-color interface (500) by introducing complementary geometries at opposing color interface edges, such as 336 and 436 or 346 and 446, to increase the stability of the interface and reduce the flow during molding associated with increased viscosity, as well as better distribute the consolidation pressure associated with expanding blowing agent embodiments. Thus, in one embodiment at least one of the interface edges (336, 346) of a first section preform (330, 340) has a first section edge geometry that cooperates with a second section edge geometry on at least one of the second section preform interface edges (436, 446) to further stabilize the interface. One example of such cooperating edge geometries is an apex geometry on one edge, shown as a first section apex geometry (360) and a second section apex geometry (460), and a cooperating receiver geometry on the abutting edge, shown as a second section receiver geometry (470) and a first section receiver geometry (370), such as seen in
In one such embodiment the apex geometry (360 or 460) has two converging sides that approach one another at a convergence angle of 120 degrees or less, which in a further embodiment is 90 degrees or less, and is 60 degrees or less in an even further embodiment, shown as a first section convergence angle (362) or a second section convergence angle (462). In another embodiment each side has a straight section that is at least 0.250″ long, while in another embodiment each straight section is at least 0.375″ long, and in yet an even further embodiment the length of the apex geometry along the longitudinal axis of the golf grip (10) is at least 70% of the maximum transverse width of the apex geometry. In the embodiment of
In another embodiment, such as that seen in
In one embodiment the tip of the apex geometry is located on a flat portion of a putter embodiment of the golf grip (10), where one, or both, of the thumbs are generally placed while gripping a putter grip, such as that seen in
The disclosed locations of the apex tip, as well as the incorporation of angled, or converging, sides and/or concave/convex portions, not only increases the contact area of abutting preforms opposing color interface edges, such as 336 and 436 or 346 and 446, and increase the stability of the interface and reduce the flow during molding associated with increased viscosity, but these features also direct and control material expansion during molding as the consolidation pressure builds by reducing directly opposing consolidation forces at the edges which promote interface irregularity. Further, these features reduce rubber migration during molding, particularly during the degassing phase during which the mold is opened and closed several times during the first minute of the molding process.
As seen in
All of these complementary geometry embodiments at opposing color interface edges, such as 336 and 436 or 346 and 446, increase the stability of the interface and reduce the flow during molding associated with increased viscosity, promote cross-linking of the sections, and better distribute the consolidation pressure associated with expanding blowing agent embodiments, to better achieve a sharply defined cross-color interface (500), particularly when at least a portion of the thickness of a preform, such as, for example, the first section top preform (330) and the second section top preform (430), along a cross-color interface edge, such as, for example, the first section top preform interface edge (336) and the second section top preform interface edge (436), is greater than 0.125 inch. Thus, in one embodiment at least a portion of the thickness of a preform, such as, for example, the first section top preform (330) and the second section top preform (430), along a cross-color interface edge, such as, for example, the first section top preform interface edge (336) and the second section top preform interface edge (436), is greater than 0.125 inch, while in another embodiment at least a portion of the thickness along the cross-color interface edge is at least 0.200 inch, and is at least 0.250 inch in an even further embodiment; which may be achieved with a single layer preform at the interface edge, or in some embodiments include multiple preform layers at the interface edge. As one skilled in the art will appreciate, embodiments having multiple preform layers, or significant variations of the exterior surface cross-sectional radius (154) seen in
Traditional opposing, or cross-color, interface edges are generally of a skived configuration, in other words they overlap to some degree. Such overlapping at the interface, particularly one associated with the soft low-density materials, which exhibiting higher viscosity during molding, disclosed herein, promotes instability and movement at the interface, as well as pigment migration. As seen in
In a further embodiment the density of at least one of the preforms is less than 0.85 g/cc and the overall golf grip (10) density is less than 0.90 g/cc; while in another embodiment at least one of the preforms has a density of less than 0.80 g/cc and the overall golf grip (10) density is less than 0.85 g/cc; and in yet another embodiment the density of all of the preforms is 0.60-0.90 g/cc and the overall golf grip (10) density is 0.75-0.90 g/cc. In still further embodiments any of the sections may further include materials to create a corded grip structure, as would be understood by one of skill in the art.
It is worth noting that the embodiments described herein with respect to a first section (300) and a second section (400) are not limited to two sections. For instance it is easy to visualize the transversely divided golf grip (10) of
The present embodiments not only achieve the desired sharply defined cross-color interface (500) along the intersection of the differing colors of the first section (300) and the second section (400), but also provide the interface stability necessary to ensure a strong failure resistant cross-color interface (500). For example, a first section test specimen (350), seen in
Each of the three interface test specimens (550) failed away from the sharply defined cross-color interface (500), as shown in
The interface transition zone (510) was previously defined as the region that is within 0.150 inch on either side of these interface edges, as seen in
A further benefit of the present golf grip (10) is improved feel. Traditionally compression molded elastomer compound grips feel hard or firm, which is undesirable in a putter grip. Further, the hardness or softness of a golf grip is best reflected using a compression test mimicking what a player actually feels when the grip is installed on a club rather than based solely on material property tests. Thus, the goal of an embodiment is to produce a soft compression molded golf grip (10) that is pleasing to the touch. A soft low-density compression molded elastomer compound golf grip (10) that compresses when squeezed by the fingers or hand can provide a comfort and training aid for golfers. After all, the putting stroke is best executed when the golfer is in a relaxed state. This occurs when the grip pressure squeezing the putter grip is light. Having a soft compressible putter grip reminds the golfer to relax the grip pressure. If the golf grip (10) can be compressed, then the golfer is reminded that they are exerting too high a grip pressure. However, a soft low-density compression molded elastomer compound golf grip (10) must also be resilient. In other words, when grip pressure is relaxed, the compressed material must return to its original shape and volume; if it doesn't, it will be considered nonconforming by the rules of golf. Thus, a golf grip must not be permanently deformable, otherwise the golfer can create a custom shaped grip to position and align the hands, which is not allowed. The present elastomer compounds are thermoset based. The vulcanization process creates a cross linking of the polymer chains that is strong and resilient. Therefore a thermoset elastomer compound may be molded in a low durometer formula and retain resiliency better than thermoplastic materials.
Next, a compression test procedure will be outlined and explained to determine the softness of a compression molded golf grip (10) at various depths or states of compression. The test fixture (600), seen in
Thus, in one embodiment a compression ratio of the compressive force, in Newton, to the compression distance, in inches, does not exceed 300 N/inch throughout a compression depth range of 0.01″ to 0.05″; whereas in another embodiment the compression ratio does not exceed 250 N/inch throughout a compression depth range of 0.01″ to 0.05″; while in another embodiment the compression ratio does not exceed 225 N/inch throughout a compression depth range of 0.01″ to 0.05″; and in yet another embodiment the compression ratio does not exceed 205 N/inch throughout a compression depth range of 0.01″ to 0.04″. In yet another embodiment the slope of the line representing the compressive force in the Y-axis and the compression depth in the X-axis, as seen in
In a further embodiment the compression ratio is 100-300 N/inch throughout a compression depth range of 0.01″ to 0.05″; whereas in another embodiment the compression ratio is 125-250 N/inch throughout a compression depth range of 0.01″ to 0.05″; while in another embodiment the compression ratio is 150-225 N/inch throughout a compression depth range of 0.01″ to 0.05″; and in yet another embodiment the compression ratio is 125-205 N/inch throughout a compression depth range of 0.01″ to 0.04″. In yet another embodiment the slope of the line representing the compressive force in the Y-axis and the compression depth in the X-axis, as seen in
Another important factor in the golf swing is the ability to have proper feel. As seen in
The cross-sectional radius (154) is the radius from the center of the central opening in the golf grip (10) to the exterior surface (110). In one embodiment specifically directed to a putter grip, at least one point along the length of the golf grip (10) has a cross-sectional radius (154) of at least 0.46 in, while in a further embodiment throughout at least 50% of the length of the golf grip (10) a cross-sectional radius (154) is at least 0.46 in, and in yet another embodiment this is true throughout at least 85% of the length of the golf grip (10). In a further embodiment, at least one point along the length of the golf grip (10) has a cross-sectional radius (154) of at least 0.525 in, while in a further embodiment the golf grip (10) has a cross-sectional radius (154) of at least 0.525 in throughout at least 50% of the length of the golf grip (10), while in a further embodiment each cross-section throughout at least 85% of the length of the golf grip (10) has a cross-sectional radius (154) of at least 0.525 in. In a further relatively non-tapered embodiment at least 50% of the length of the golf grip (10) has cross-sections containing a cross-sectional radius (154) of 0.46-0.80 in; while in another embodiment at least 85% of the length of the golf grip (10) has cross-sections containing a cross-sectional radius (154) of 0.46-0.80 in.
A further oversized putter grip embodiment has at least one point along the length of the golf grip (10) has a cross-section having a cross-sectional area (152) of at least 5.25 cm2, while in a further embodiment at least 50% of the length of the golf grip (10) has a cross-section having a cross-sectional area (152) of at least 5.25 cm2. Still further, one embodiment has 85% of the length of the golf grip (10) possesses cross-sections having a cross-sectional area (152) of at least 5.25 cm2. In one embodiment specifically directed to an oversized putter grip, at least one point along the length of the golf grip (10) has a cross-sectional radius (154) of at least 0.55 in, while in a further embodiment at least 50% of the length of the golf grip (10) has cross-sections having a cross-sectional radius (154) of at least 0.55 in. Still further, one embodiment has 85% of the length of the golf grip (10) having cross-sections with a cross-sectional radius (154) of at least 0.55 in. In a further relatively non-tapered embodiment at least 50% of the length of the golf grip (10) has cross-sections having a maximum cross-sectional radius (154) of 0.55-0.90 in; while in another embodiment at least 85% of the length of the golf grip (10) has cross-sections having a maximum cross-sectional radius (154) of 0.55-0.90 in. Further, in another embodiment at least one point on the exterior surface (110) has a cross-sectional radius (154) of at least 0.65 inches, while in another embodiment at least one point on the exterior surface (110) has a cross-sectional radius (154) of at least 0.75 inches.
Additionally, another putter grip embodiment has a volume of at least 100 cc and a weight of 50-145 grams, while a further embodiment has a volume of 100-130 cc and a weight of 55-120 grams, while a further embodiment has a volume of at least 135 cc and a weight of 90-160 grams, and an even further embodiment has a volume of 135-160 cc and a weight of 120-145 grams. In one embodiment the overall density of the entire golf grip (10) is 0.45-0.89 g/cc, while in a further embodiment the overall density of the entire golf grip (10) is 0.60-0.89 g/cc, and in an even further embodiment the overall density of the entire golf grip (10) is 0.70-0.89 g/cc.
As previously touched upon, the golf grip (10) may be formed of a plurality of layers in one or both sections (300, 400), including at least a first layer and a second layer. The individual layers may be adhered to each other, or joined in the compression molding process. In one such embodiment the first layer has a first layer thickness and the second layer has a second layer thickness, both being thicknesses measured before the actual manufacturing process, thus an uncured thickness. A further embodiment has a first layer thickness that is at least 25% greater than a second layer thickness. In one embodiment the first layer thickness is 1.50-3.00 mm and the second layer thickness is 1.25-2.50 mm; while in a further embodiment the first layer thickness is 2.00-2.80 mm and the second layer thickness is 1.70-2.25 mm; and in yet another embodiment the first layer thickness is 2.30-2.70 mm and the second layer thickness is 1.80-2.00 mm. Further, the first layer and the second layer may contain different quantities of blowing agent causing them to expand differently during the compression molding curing process. For instance, in one example the first layer has a quantity of blowing agent that is at least twice the quantity of blowing agent in the second layer; while in a further embodiment the first layer has a quantity of blowing agent that is at least 2.5 times the quantity of blowing agent in the second layer; and in an even further embodiment the first layer has a quantity of blowing agent that is at least 3 times the quantity of blowing agent in the second layer.
In addition to the two layer embodiment just described, a further embodiment includes a third layer, having a third layer thickness, located between the first layer and the second layer. Including a third layer may increase the precision of the manufacturing process. As with the two layer embodiments, the individual layers may be adhered to each other, or joined in the compression molding process. Again, the individual layer thicknesses discussed herein are measured before the actual manufacturing process, thus an uncured thickness. In one embodiment both the first layer thickness and the third layer thickness are less than the second layer thickness; in fact, in a further embodiment both the first layer thickness and the third layer thickness are at least 20% less than the second layer thickness. In an even further embodiment both the first layer thickness and the third layer thickness are at least 50-75% of the second layer thickness. In yet another embodiment the first layer thickness and the third layer thickness are 1.00-1.50 mm and the second layer thickness is 1.25-2.50 mm; while in a further embodiment the first layer thickness and the third layer thickness are 1.25-1.40 mm and the second layer thickness is 1.70-2.25 mm; and in yet another embodiment the first layer thickness and the third layer thickness are 1.30-1.35 mm and the second layer thickness is 1.80-2.00 mm. In one embodiment the third layer has a quantity of blowing agent that is at least twice the quantity of blowing agent in the second layer; while in a further embodiment the third layer has a quantity of blowing agent that is at least 2.5 times the quantity of blowing agent in the second layer; and in an even further embodiment the third layer has a quantity of blowing agent that is at least 3 times the quantity of blowing agent in the second layer.
In another embodiment both the first layer thickness and the second layer thickness are less than the third layer thickness; in fact, in a further embodiment both the first layer thickness and the second layer thickness are at least 20% less than the third layer thickness. In an even further embodiment both the first layer thickness and the second layer thickness are less than half of the maximum third layer thickness. In yet another embodiment the first layer thickness and the second layer thickness are less than 1.50 mm and the third layer thickness is at least 2.00 mm; while in a further embodiment the first layer thickness is less than 20% of the maximum third layer thickness and the first layer thickness is less than 50% of the maximum second layer thickness. In an even further embodiment the first layer thickness is less than 0.50 mm, the second layer thickness is at least 0.75 mm, and the third layer thickness is 1.5-8.0 mm.
Further, in these three layer embodiments the first layer, the second layer, and the third layer may contain different quantities of blowing agent causing them to expand differently during the compression molding curing process. For instance, in one example the first layer and the third layer each have a quantity of blowing agent that is at least twice the quantity of blowing agent in the second layer; while in a further embodiment the first layer and the third layer each have a quantity of blowing agent that is at least 2.5 times the quantity of blowing agent in the second layer; while in an even further embodiment the first layer and the third layer each have a quantity of blowing agent that is at least 3 times the quantity of blowing agent in the second layer; while in yet an even further embodiment the first layer and the third layer each have a quantity of blowing agent that is 3-6 times the quantity of blowing agent in the second layer; and in an even further embodiment the first layer and the third layer each have a quantity of blowing agent that is 4-5.5 times the quantity of blowing agent in the second layer. The blowing agents previously discussed are also applicable to this third layer, as are the material compositions and characteristics of the first layer.
The quantity of blowing agent and the compression molding process parameters affect the density, porosity, and hardness of the regions of the golf grip (10). The golf grip (10) may be compression molded using the layers previously discussed. Strips of the layers are positioned in both halves of the compression mold (M), about a core rod (R), in an arrangement corresponding to that desired in the finished grip. A core rod (CR), or mandrel, is positioned in the half mold to facilitate forming the hollow tubular golf grip (10). The compression half molds are clamped together and heated to a temperature that vulcanizes and joins the layers together into the tubular form of the finished golf grip (10). In some embodiment the core rod (CR) is heated, or warmed, to a temperature of at least 120° C. to also promote curing from the interior surface (120).
The golf grip (10) embodiments disclosed herein may also include a butt cap (600) and/or a tip cap (700), as seen in
Numerous alterations, modifications, and variations of the preferred embodiments disclosed herein will be apparent to those skilled in the art and they are all anticipated and contemplated to be within the spirit and scope of the instant invention. For example, although specific embodiments have been described in detail, those with skill in the art will understand that the preceding embodiments and variations can be modified to incorporate various types of substitute and or additional or alternative materials, relative arrangement of elements, and dimensional configurations. Accordingly, even though only few variations of the present invention are described herein, it is to be understood that the practice of such additional modifications and variations and the equivalents thereof, are within the spirit and scope of the invention as defined in the following claims. Further, the use of exterior surface (110) throughout does not preclude a cosmetic or decorative coating of 1 mm thickness, or less, over the structural exterior surface (110). The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or acts for performing the functions in combination with other claimed elements as specifically claimed.
This application is a continuation of U.S. nonprovisional application Ser. No. 16/502,593, filed on Jul. 3, 2019, now U.S. Pat. No. 10,729,953, which is a continuation of U.S. nonprovisional application Ser. No. 16/010,557, filed on Jun. 18, 2018, now U.S. Pat. No. 10,343,039, which is a divisional application of U.S. nonprovisional application Ser. No. 14/964,384, filed on Dec. 9, 2015, now U.S. Pat. No. 9,999,815, all of which is incorporated by reference as if completely written herein.
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