US20120088606A1

US20120088606A1 - Multi-layer golf ball having thermoplastic vulcanized elastomers forming inner cover or intermediate cover layers

Info

Publication number: US20120088606A1
Application number: US13/333,361
Authority: US
Inventors: Murali Rajagopalan; Michael J. Sullivan; Derek A. Ladd; Mark L. Binette
Original assignee: Acushnet Co
Current assignee: Acushnet Co
Priority date: 2009-03-06
Filing date: 2011-12-21
Publication date: 2012-04-12

Abstract

A golf ball including a core and a cover disposed about the core, the cover comprising three layers, an inner cover layer, an intermediate layer, and an outer cover layer. The core having a first hardness, the inner cover layer having a second hardness, and the intermediate layer having a third hardness, wherein the ratio of the second hardness to the third hardness is between 0.70 to 0.97 and at least one of the inner cover layer or the intermediate layer being formed from a rigid thermoplastic vulcanized elastomer composition.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of co-pending U.S. patent application Ser. No. 12/399,322, filed Mar. 6, 2009, the disclosure is incorporated by reference herein in its entirety.

FIELD OF THE INVENTION

This invention relates generally to golf balls having a multi-layer cover. More specifically, at least one of an intermediate cover layer of an inner cover layer is formed of a thermoplastic vulcanized elastomer material.

BACKGROUND OF THE INVENTION

The majority of golf balls commercially available today are of a solid construction. Solid golf balls include one-piece, two-piece, and multi-layer golf balls. One-piece golf balls are inexpensive and easy to construct, but have limited playing characteristics and their use is, at best, confined to the driving range. Two-piece golf balls are generally constructed with a solid polybutadiene core and a cover and are typically the most popular with recreational golfers because they are very durable and provide good distance. These golf balls are also relatively inexpensive to make, but are regarded by top players as having limited playing characteristics. Multi-layer golf balls are comprised of a solid core and a cover, either of which may be formed of one or more layers. These balls are regarded as having an extended range of playing characteristics, but are more expensive and difficult to manufacture than are one- and two-piece golf balls.
Wound golf balls, which typically included a fluid-filled center surrounded by a layer of tensioned elastomeric material and a cover, were preferred for their spin and “feel” characteristics but were more difficult and expensive to manufacture than solid golf balls. Manufacturers are continuously striving to produce a solid ball that concurrently includes the beneficial characteristics of a wound ball.
Golf ball playing characteristics, such as compression, velocity, and spin can be adjusted and optimized by manufacturers to suit players having a wide variety of playing abilities. For example, manufacturers can alter any or all of these properties by changing the materials and/or the physical construction of each or all of the various golf ball components (i.e., centers, cores, intermediate layers, and covers). Finding the right combination of core and layer materials and the ideal ball construction to produce a golf ball suited for a predetermined set of performance criteria is a challenging task.
Efforts to construct a multi-layer golf ball have generally focused on the use of one or two cover layers formed of ionomeric and/or polyurethane compositions. It is desirable, therefore, to construct a golf ball wherein the outer cover layer is formed either from a thermoplastic ionomer or from a castable thermoset composition like the thermoset polyurethane or polyurea or epoxy or the cross-linkable rubber compositions, and at least one inner cover layer is constructed such that there is a reduction in the spin rates from a driver, without sacrificing its resiliency and impact durability. In particular, it is desired that this construction include a thin, stiff, high-hardness thermoplastic non-ionomeric material.

SUMMARY

The present invention is directed to a golf ball including a core and a cover disposed about the core. The cover is a three-layer cover and includes an inner cover layer, an intermediate layer and an outer cover layer. The core having a first shore D hardness. The inner cover layer is disposed directly about the core and has a second hardness. The intermediate cover layer is disposed between the inner and outer cover layers and has a third shore D hardness, and at least one of the inner cover or intermediate layers being formed from a rigid thermoplastic vulcanized elastomer composition, wherein a ratio of the second Shore D hardness to the third Shore hardness is between 0.70 to 0.97, preferably between 0.75 to 0.95, and more preferably between 0.80 to 0.92. The outer cover layer is formed from a castable thermoset composition selected from a group consisting of polyurethane or polyurea or epoxy or cross-linkable rubber compositions, wherein the cover layer comprises a Shore D hardness of 40 to 60 and a flexural modulus of 15 to 45 kpsi.
In one construction, the inner cover layer is formed from a rigid thermoplastic vulcanized composition selected from either an aliphatic or aromatic copoly group consisting of ether-urethane or ether-urea or ester-urethane or ester-urea, or ether-ester-urethane or ether-ester-urea, or caprolactone-urethane or caprolactone-urea elastomers and their blends. The inner cover layer has a Shore D hardness of 55 to 65 and the intermediate layer has a shore D hardness of 60 to 75, and wherein the intermediate layer may be formed from thermoplastics including ionomers, highly neutralized polymers, and non-ionomers.
In another embodiment, the inner cover layer is formed from a rigid thermoplastic vulcanized elastomer composition selected from a copoly group consisting of ether-amide or ester-amide or ether-ester-amide elastomers and their blends. The inner cover layer having a shore D hardness of 55 to 65 and a thermoplastic intermediate layer disposed over the inner cover layer being formed from compositions that include ionomers, highly neutralized polymers, as well as non-ionomers has a shore D hardness of 60 to 75.
In an alternate construction, the intermediate layer is formed from a rigid thermoplastic vulcanized elastomer composition selected from either an aromatic or aliphatic copoly group consisting of ether-urethane or ether-urea or ester-urethane or ester-urea, or ether-ester-urethane or ether-ester-urea, or caprolactone-urethane or caprolactone-urea elastomers and their blends having a Shore D hardness of 60 to 75 and the inner cover layer being a thermoplastic which may include ionomers, highly neutralized polymers, or non-ionomers and having a shore D hardness of 55 to 65 and a flexural modulus of 50 to 60 kpsi.
The present invention is also directed to a golf ball wherein the intermediate layer is formed from a rigid thermoplastic vulcanized composition selected from a copoly group consisting of ether-amide or ester-amide or ether-ester-amide elastomers and their blends having a Shore D hardness of 60 to 75 and the inner cover layer being thermoplastic including ionomers, highly neutralized polymers, non-ionomers having a shore D hardness of 55 to 65 and a flexural modulus of 50 to 60 kpsi.
The present invention is further directed to a golf ball, wherein both the inner cover and intermediate layers are formed from the thermoplastic vulcanized composition selected from either an aromatic or aliphatic copoly group consisting of ether-urethane or ether-urea or ester-urethane or ester-urea, or ether-ester-urethane or ether-ester-urea, or caprolactone-urethane or caprolactone-urea elastomers and their blends, with the inner cover layer having a Shore D hardness or about 45 to 70 and a flexural modulus of about 30 to 80 kpsi, and the intermediate layer having a Shore D hardness of about 50 to 75 and a flexural modulus of about 40 to 100 kpsi.
In another preferred embodiment, both the inner cover and intermediate layers are formed from the thermoplastic vulcanized composition selected from the copoly group consisting of ether-amide or ester-amide or ether-ester-amide elastomers and their blends with the innermost layer having a Shore D hardness or about 45 to 70 and a flexural modulus of about 30 to 80 kpsi, and the intermediate layer having a
Shore D hardness of about 50 to 75 and a flexural modulus of about 40 to 100 kpsi.
In yet still another embodiment, the core of the ball has a diameter of 0.70 to 1.58 inches, and preferably 1.45 to 1.55 inches. The inner cover layer has a thickness of about 0.030 to 0.070 inches, more preferably a thickness of about 0.030 to 0.050 inch, while the intermediate layer has a thickness of about 0.010 to 0.080 inches, more preferably 0.020 to 0.050 inches. The inner cover and intermediate layers may have a moisture barrier material about them to provide an improved shelf-life for the ball performance.

DESCRIPTION OF THE PREFERRED EMBODIMENT

A golf ball of the present invention includes a core and a three-piece cover that comprises an outer cover and at least two inner layers, such as an inner cover layer and an intermediate cover layer disposed between the outer cover layer and the inner cover layer. The golf ball cores of the present invention may be formed with a variety of constructions. For example, the core may include a plurality of layers, such as a center and an outer core layer. The core, while preferably solid, may comprise a liquid, foam, gel, or hollow center. The golf ball may also include a layer of tensioned elastomeric material, for example, located between the core and triple cover. In a preferred embodiment, the core is a solid core.
Materials for solid cores include compositions having a base rubber, a filler, an initiator agent, and a cross-linking agent. The base rubber typically includes natural or synthetic rubber, such as polybutadiene rubber. A preferred base rubber is 1,4-polybutadiene having a cis-structure of at least 40%. Most preferably, however, the solid core is formed of a resilient rubber-based component comprising a high-Mooney-viscosity rubber and a crosslinking agent.
Another suitable rubber from which to form cores of the present invention is trans-polybutadiene. This polybutadiene isomer is formed by converting the cis-isomer of the polybutadiene to the trans-isomer during a molding cycle. Various combinations of polymers, cis-to-trans catalysts, fillers, crosslinkers, and a source of free radicals, may be used. A variety of methods and materials for performing the cis-to-trans conversion have been disclosed in U.S. Pat. Nos. 6,162,135; 6,465,578; 6,291,592; and 6,458,895, each of which are incorporated herein, in their entirety, by reference.
Additionally, without wishing to be bound by any particular theory, it is believed that a low amount of 1,2-polybutadiene isomer (“vinyl-polybutadiene”) is preferable in the initial polybutadiene to be converted to the trans- isomer. Typically, the vinyl polybutadiene isomer content is less than about 7 percent, more preferably less than about 4 percent, and most preferably, less than about 2 percent.
Fillers added to one or more portions of the golf ball typically include processing aids or compounds to affect rheological and mixing properties, the specific gravity (i.e., density-modifying fillers), the modulus, the tear strength, reinforcement, and the like. The fillers are generally inorganic, and suitable fillers include numerous metals or metal oxides, such as zinc oxide and tin oxide, as well as barium sulfate, zinc sulfate, calcium carbonate, barium carbonate, clay, tungsten, tungsten carbide, an array of silicas, and mixtures thereof. Fillers may also include various foaming agents or blowing agents, zinc carbonate, regrind (recycled core material typically ground to about 30 mesh or less particle size), high-Mooney-viscosity rubber regrind, and the like. Polymeric, ceramic, metal, and glass microspheres may be solid or hollow, and filled or unfilled. Fillers are typically also added to one or more portions of the golf ball to modify the density thereof to conform to uniform golf ball standards. Fillers may also be used to modify the weight of the center or any or all core and cover layers, if present.
The initiator agent can be any known polymerization initiator which decomposes during the cure cycle. Suitable initiators include peroxide compounds such as dicumyl peroxide, 1,1-di(t-butylperoxy) 3,3,5-trimethyl cyclohexane, a-a bis(t-butylperoxy) diisopropylbenzene, 2,5-dimethyl-2,5 di(t-butylperoxy) hexane or di-t-butyl peroxide and mixtures thereof.
Cross-linkers are included to increase the hardness and resilience of the reaction product. The cross-linking agent includes a metal salt of an unsaturated fatty acid such as a zinc salt or a magnesium salt of an unsaturated fatty acid having 3 to 8 carbon atoms such as acrylic or methacrylic acid. Suitable cross linking agents include metal salt diacrylates, dimethacrylates and monomethacrylates wherein the metal is magnesium, calcium, zinc, aluminum, sodium, lithium or nickel. Preferred acrylates include zinc acrylate, zinc diacrylate, zinc methacrylate, and zinc dimethacrylate, and mixtures thereof.
The cross-linking agent must be present in an amount sufficient to crosslink a portion of the chains of polymers in the resilient polymer component. This may be achieved, for example, by altering the type and amount of cross-linking agent, a method well-known to those of ordinary skill in the art.
When the core is formed of a single solid layer comprising a high-Mooney-viscosity rubber, the cross-linking agent is present in an amount from about 15 to about 40 parts per hundred, more preferably from about 30 to about 38 parts per hundred, and most preferably about 37 parts per hundred.
In another embodiment of the present invention, the core comprises a solid center and at least one outer core layer. When the optional outer core layer is present, the center preferably comprises a high-Mooney-viscosity rubber and a cross-linking agent present in an amount from about 10 to about 30 parts per hundred of the rubber, preferably from about 19 to about 25 parts per hundred of the rubber, and most preferably from about 20 to 24 parts cross-linking agent per hundred of rubber. Suitable commercially-available polybutadiene rubbers include, but are not limited to, CB23, CB22, Taktene® 220, and Taktene® 221, from Lanxess Corp.; Neodene® 40 and Neodene® 45 from Karbochem Ltd.; LG1208 from LG Corp. or Korea; and Cissamer® 1220 from Basstech Corp. of India. Other rubbers, such as butyl rubber, chloro or bromyl butyl rubber, styrene butadiene rubber, or trans polyisoprene may be added to the polybutadiene for property or processing modification.
Additionally, the unvulcanized rubber, such as polybutadiene, typically has a Mooney viscosity of between about 40 and about 80, more preferably, between about 40 and about 60, and most preferably, between about 40 and about 55. Mooney viscosity is typically measured according to ASTM D-1646.
The polymers, free-radical initiators, filler, cross-linking agents, and any other materials used in forming either the golf ball center or any portion of the core, in accordance with invention, may be combined to form a mixture by any type of mixing known to one of ordinary skill in the art. Suitable types of mixing include single pass and multi-pass mixing, and the like. The cross-linking agent, and any other optional additives used to modify the characteristics of the golf ball center or additional layer(s), may similarly be combined by any type of mixing. A single-pass mixing process where ingredients are added sequentially is preferred, as this type of mixing tends to increase efficiency and reduce costs for the process. The preferred mixing cycle is single step wherein the polymer, cis-to-trans catalyst, filler, zinc diacrylate, and peroxide are added sequentially.
As previously stated, the cover of the present invention golf ball is a multi-layer cover, preferably comprised of at least three layers, such as an inner cover layer, an intermediate cover layer, and an outer cover layer. While the various cover layers of the present invention may be of any individual thickness, it is preferred that the combination of cover layer thicknesses be no greater than about 0.125 inches, more preferably, no greater than about 0.105 inches, and most preferably, no greater than about 0.09 inches.
In the instant invention the core of the golf ball has a first shore D hardness, the inner cover layer has a second Shore D harness and an intermediate layer has a third shore D hardness on the surface of the ball, wherein hardness ratio of the second shore D to the third shore D is in the range 0.70 to 0.97, and preferably 0.75 to 0.93. The inner cover layer or intermediate layer or both layers are formed from a rigid thermoplastic vulcanized aromatic or aliphatic copoly (ether-urethane or urea) or copoly (ester-urethane or urea) or copoly (ether-ester-urethane or urea) or copoly (capriolactone-urethane or urea) elastomers and their blend compositions. The vulcanized thermoplastic could also be a copoly (ether-amide) or copoly (ester-amide) or copoly (ether-ester-amide) elastomers and their blend compositions. The outer cover layer is formed from a castable thermoset or a post cross-linked thermoplastic. Optionally, the inner cover and intermediate layers are covered with a moisture barrier material to provide for improved shelf-life for the ball performance.
The result of the presence of rigid vulcanized cross-links present in the thermoplastic vulcanized polyurethane or polyurea or polyamide elastomer compositions will improve the golf ball performance such as the coefficient of restitution (COR) from the driver and long irons without significantly affecting he compression. This is significant when compared to conventional thermoplastic polyurethane or polyurea or polyamide elastomers.
In a first embodiment of a three cover ball, a rigid thermoplastic vulcanized copoly is selected from one of the following: copoly ether amide, copoly ester-amide, aliphatic or aromatic copolys selected from ether-urethane or copoly ether-urea, or copoly ester-urethane or copoly ester-urea or copoly ether-ester-urethane or copoly ether-ester-urea and their impact modified blend compositions having a Shore D hardness of 55 to 65 and a flexural modulus of 50 to 60 kpsi. These compositions are used in the inner cover layer to improve a balance of golf properties including a distance off the tee, a good control in the short game along with good impact resistance. The intermediate layer in this type of construction is selected from a rigid thermoplastic ionomers and non-ionomers including acid copolymers, thermoset materials including castable thermoset compositions having a Shore D hardness of 60 to 75 and a flexural modulus of 55 to 80 kpsi, while maintaining a ratio of the second shore D hardness to the third Shore D hardness in the range of 0.70 to 0.97, and preferably 0.75 to 0.93. An outer cover layer is formed from a castable thermoset composition including a thermoset polyurethane and polyurea or a post cross-liked thermoplastic having a Shore D hardness of 40 to 60 and a flexural moduus for 15 to 45 kpsi.
Another preferred embodiment of the invention presents a three cover ball wherein the intermediate cover layer contains a rigid thermoplastic vulcanized copoly selected from copoly ether amide or copoly ester-amide or aliphatic or aromatic copolys selected from ether-urethane or copoly ether-urea, or copoly ester-urethane or copoly ester-urea or copoly ether-ester-urethane or copoly ether-ester-urea and their impact modified blend compositions to provide a balance of golf properties, such as distance, control, and durability. In this embodiment the inner cover layer is selected from rigid thermoplastic ionomers and non-ionomers as well as thermoset materials including castable and cross-linked rubber compositions having a Shore D hardness of 55 to 65 and a flexural modulus of 50 to 60 kpsi while still maintaining a ratio of the second to third Shore D hardness in the range of 0.70 to 0.97, preferably 0.75 to 0.93.
Another embodiment provides for both the inner cover and intermediate layers to be formed of the previously mentioned thermoplastic vulcanized copoly, such as a copoly selected from copoly ether amide or copoly ester-amide or aliphatic or aromatic copolys selected from ether-urethane or copoly ether-urea, or copoly ester-urethane or copoly ester-urea or copoly ether-ester-urethane or copoly ether-ester-urea and their impact modified blend compositions, provided that they have distinct differences in their material properties such as hardness, flexural modulus (i.e. innermost cover is softer than intermediate cover.
Yet another embodiment of the invention provides for a golf ball consisting of only two cover layers, the outer and the intermediate. In this case it is the intermediate cover layer that is constructed of the thermoplastic vulcanized copoly, such as a copoly selected from copoly ether amide or copoly ester-amide or aliphatic or aromatic copolys selected from ether-urethane or copoly ether-urea, or copoly ester-urethane or copoly ester-urea or copoly ether-ester-urethane or copoly ether-ester-urea and their impact modified blend compositions. In this instance either the intermediate cover layer or the core layer is further covered with a thin moisture barrier layer to provide an improved shelf life by protecting these layers from moisture. The cover layer from this construction is selected from rigid thermoplastic ionomers and non-ionomers as well as thermoset materials including castable and cross-linked rubber compositions well known in the golf ball industry.

PROPHETIC EXAMPLE 1

A rigid thermoplastic vulcanized material based on Pebax 5533 with either an in-situ cross-linked rubber composition based on a cross-linkable rubber like an acrylate or a nitrile or butyl rubber or fluoroelastomer or CPE or colorprene etc., an initiator and co-agents or a physical mixture of Pebax 5533 with a pre-cross-linked rubber molded over a 1.500 inch solid cross-lined butyl core to provide an innermost cover layer thickness of about 0.040 inches. This was followed by molding a rigid intermediate cover layer based on thermoplastic or thermoset polymers such as polycarbonate/polyester, or polycarbonate/polyamide, or polycarbonate/polyurethane, Pebax, ionomers, acid copolymers, thermoplastic urethane (TPU), a castable thermoset polyurethane or polyurea. In this example, a blend of Pebax 6533 with an acid copolymer such as Clarix 01740 (a copolymer of E-17% AA was molded over an inner cover layer to provide an intermediate cover layer having a thickness of about 0.020 inches. A castable thermoset liquid material such as a polyurethane or polyurea was molded over an intermediate cover layer to provide a golf ball having a compression of about 90 to 115, preferably about 95-110 and more preferably 100 to 110. This golf ball has a coefficient of restitution (CoR) of about 0.795 to 0.813, preferably of about 0.800 to 0.812 and most preferably of about 0.802 to 0.810.

PROPHETIC EXAMPLE 2

A rigid thermoplastic vulcanized material based on Texin DP7-1201 with either an in-situ cross-linked rubber composition based on across-linkable rubber like an acrylate or a nitrile or butyl rubber or fluoroelastomer or CPE or colorprene etc., an initiator and co-agents or a physical mixture of Texin DP7-1202 with a pre-cross-linked rubber molded over a 1.500 inch solid cross-lined BR core to provide an inner cover layer thickness of about 0.040 inches. This was followed by molding a rigid intermediate cover layer based on thermoplastic or thermoset polymers such as polycarbonate/polyester, or polycarbonate/polyurethane, or polycarbonate/polyurea, or Pebax, or ionomers, or acid copolymers, or TPU, or a castable thermoset such as polyurethane or polyurea. In this example, Texin DP7-1193 was molded over an inner cover layer to provide an intermediate cover layer having a thickness of about 0.020 inches. A castable thermoset liquid material such as a polyurethane or polyurea was molded over the intermediate cover layer to provide a golf ball having a compression of about 90 to 115, preferably about 95-110 and more preferably 100 to 110. This golf ball has a CoR of about 0.795 to 0.813, preferably of about 0.800 to 0.812 and most preferably of about 0.802 to 0.810.

PROPHETIC EXAMPLE 3

A rigid inner cover layer based on a thermoplastic or thermoset polymers such as polycarbonate/polyester, polycarbonate/polyamide, polycarbonate/polyurethane, Pebax, ionomers, acid copolymers, TPU, a castable thermoset polyurethane or polyurea was molded over a molded over a 1.500 inch solid cross-lined butyl rubber core to provide an innermost cover layer thickness of about 0.040 inches. In this example, a rigid thermoplastic vulcanized material based on Pebax 6533 with either an in-situ cross-linked rubber composition based on a cross-linkable rubber, an initiator and co-agents or a physical mixture of Pebax 6533 with a cross-linked rubber was molded over the inner cover layer to provide an intermediate cover layer having a thickness of about 0.020 inches. A castable thermoset polyurethane or polyurea layer was molded over an intermediate cover layer to provide a golf ball having a compression of about 90 to 120, preferably about 95-115 and more preferably 100 to 115. This golf ball has a CoR of about 0.795 to 0.813, preferably of about 0.800 to 0.813 and most preferably of about 0.802 to 0.808.

PROPHETIC EXAMPLE 4

A rigid inner cover-layer based on a thermoplastic or thermoset polymers such as polycarbonate/polyester, polycarbonate/polyurethane, polycarbonate/polyurea, Pebax, ionomers, acid copolymers, TPU, a castable thermoset polyurethane or polyurea. was molded over a 1.500 inch solid cross-lined butyl rubber core to provide an innermost cover layer thickness of about 0.040 inches. This was followed by molding a rigid intermediate cover layer based on based on Texin DP7-1193 with either an in-situ cross-linked rubber composition based on a cross-linkable rubber like an acrylate or a nitrile or butyl rubber or fluoroelastomer or CPE or colorprene etc., an initiator and co-agents or a physical mixture of Texin DP7-1193 with a pre-cross-linked rubber molded over the inner cover layer to provide an intermediate cover layer of about 0.020 inch thickness. A castable thermoset polyurethane or polyurea layer was molded over an intermediate cover layer to provide a golf ball having a compression of about 90 to 120, preferably about 95-115 and more preferably 100 to 115. This golf ball has a CoR of about 0.795 to 0.813, preferably of about 0.800 to 0.813 and most preferably of about 0.802 to 0.808.
The polyurethane or polyurea component such as the isocyanate is selected from aromatic as well as aliphatic including MDI, TDI, PPHI, HDI, H12MDI, IPDI, and mixtures thereof. The ether segment is selected from an ethylene, propylene, tetramethylene glycols, and their copolymers as well as others known in the art.
Suitable vulcanized rubbers for use with the present invention include, but are not limited to, acrylate rubbers such as cross-linkable poly(meth)acrylate or polyethylene(meth)acrylate vulcanizates, nitrile rubbers, epichlorohydrin rubbers, chlorinated polyethylene, polyisoprene rubber, styrene butadiene rubber, polybutadiene rubber, butyl and halobutyl rubber, ethylene propylene or ethylene propylene diene rubber, fluorocarbon rubbers, melt processable polyurethane gum rubbers, fluorosilicone elastomers, ethyl alkyl acrylate acid, acrylic acid copolymer rubber (Vamac), polyphosphazene elastomers, polysulfide elastomers, and mixtures thereof. A skilled artisan would be aware of methods for forming a suitable vulcanized rubber for use with the present invention. For example, a vulcanization product for use with the present invention may be formed by copolymerizing more than one acrylic acid ester, methacrylic acid ester, or mixtures thereof to form poly(meth)acrylate copolymers.
In all the above embodiments, the core used in the two or three or four cover layer may be a single core or a dual core or a triple layer core formed from the cross-linkable rubber composition as well as based on a highly neutralized thermoplastic and thermoset polymer compositions.
Preferred thermoplastic polycarbonate/polyester copolymers or blends thereof include, but are not limited to, polycarbonate/poly(butylene terephthalate) (PC/PBT). Suitable PC/PBT are commercially-available under the tradenames Xylex® and Xenoy® from General Electric Corporation of Pittsfield, Mass., or Ultradur® from BASF or Makroblend® from Bayer. Xylex®-type chemistries, such as those disclosed in U.S. Pat. No. 7,358,305, the disclosure of which is incorporated herein in its entirety by reference thereto, are the most preferred intermediate cover layer materials.
The PC/PBT blend may also be modified by blending with, for example, acrylonitrile butadiene styrene (ABS) plastics. Other suitable polymers that can be used as stand alone or along with the polycarbonate/polyester copolymers and blends in accordance with this invention include, but are not limited to:
1) Polyesters, such as polybutylene terephthalate (PBT) commercially available as Crastin® from DuPont; polyethylene terephthalate, such as DuPont Rynite®; and rigid Hytrel® grades from DuPont, such as Hytrel® 3078, 4068, 5556, 6356, 7246, and 8238. Hytrel® is a block copolymer of a crystalline hard segment (i.e., PBT) and an amorphous soft segment (i.e., a polyether, such as THF). DuPont Thermx® PCT polyester is also a suitable material and is based on poly(cyclohexene-dimethylene terephthalate) chemistry.
Other suitable polyester resins include crystalline polyester resins such as polyester resins derived from an aliphatic or cycloaliphatic diol, or mixtures thereof, containing from about 2 to 10 carbon atoms and at least one aromatic dicarboxylic acid. Preferred polyesters are derived from an aliphatic diol and an aromatic dicarboxylic acid. The polyester resin may comprise one or more resins selected from linear polyester resins, branched polyester resins and copolymeric polyester resins. Suitable linear polyester resins include polyalkylene phthalates, such as polyethylene terephthalate, polybutylene terephthalate, and polypropylene terephthalate; polycycloalkylene phthalates, such as polycyclohexanedimethanol terephthalate; polyalkylene naphthalates, such as polybutylene-2,6-naphthalate and polyethylene-2,6-naphthalate; and polyalkylene dicarboxylates, such as polybutylene dicarboxylate.
Preferably, copolymeric polyester resins include polyesteramide copolymers, cyclohexanedimethanol-terephthalic acid-isophthalic acid copolymers and cyclohexanedimethanol-terephthalic acid-ethylene glycol copolymers. The polyester component can, without limitation, comprise the reaction product of a glycol portion comprising 1,4-cyclohexanedimethanol and ethylene glycol, wherein the ethylene glycol is greater than 60 mole percent based on the total moles of 1,4-cyclohexanedimethanol and ethylene glycol with an acid portion comprising terephthalic acid, or isophthalic acid or mixtures of both acids.
The copolyester may also be a copolyester where the glycol portion has a predominance of ethylene glycol over 1,4-cyclohexanedimethanol, preferably is about greater than 60 molar percent of ethylene glycol based on the total mole percent of ethylene glycol and 1,4-cyclohexanedimethanol, and the acid portion is terephthalic acid. In another embodiment of the present invention the polyester comprises structural units derived from terephthalic acid and a mixture of 1,4-cyclohexane dimethanol and ethylene glycol, wherein said ethylene glycol is greater than about 75 mole percent based on total moles of 1,4-cyclohexane dimethanol and ethylene glycol. In another embodiment, the polyester resin has an intrinsic viscosity of from about 0.4 to about 2.0 dL/g as measured in a 60:40 phenol/tetrachloroethane mixture at 23-30° C.
The polyesters may also be derived from structural units comprising xylene glycol or, alternatively, from structural units comprising at least one of o-xylene glycol, m-xylene glycol, and p-xylene glycol. Preferably, the polyester is derived from structural units comprising p-xylene glycol. The xylene glycol should be present in an amount at least greater than about 40 mole percent, more preferably from about 50 to 100 mole percent, most preferably about 100 mole percent.
The polyester may optionally comprise straight chain, branched, or cyclo-aliphatic diols containing from 2 to 12 carbon atoms. Examples of such diols include but are not limited to ethylene glycol; propylene glycol, such as 1,2- and 1,3-propylene glycol; 2,2-dimethyl-1,3-propane diol; 2-ethyl, 2-methyl, 1,3-propane diol; 1,3- and 1,5-pentane diol; dipropylene glycol; 2-methyl-1,5-pentane diol; 1,6-hexane diol; dimethanol decalin, dimethanol bicyclo octane; 1,4-cyclohexane dimethanol and particularly its cis- and trans-isomers; triethylene glycol; 1,10-decane diol; and mixtures thereof. The diol may also include glycols, such as ethylene glycol, propylene glycol, butanediol, hydroquinone, resorcinol, trimethylene glycol, 2-methyl-1,3-propane glycol, 1,4-butanediol, hexamethylene glycol, decamethylene glycol, 1,4-cyclohexane dimethanol, or neopentylene glycol. Chemical equivalents to the diols include esters, such as dialkylesters, diaryl esters, and the like.
The polyester may optionally comprise polyvalent alcohols which include, but are not limited to, an aliphatic polyvalent alcohol, an alicyclic polyvalent alcohol, and an aromatic polyvalent alcohol, including ethylene glycol, propylene glycol, 1,3-propanediol, 2,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, diethylene glycol, dipropylene glycol, 2,2,4-trimethyl-1,3-pentanediol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, trimethylolethane, trimethylolpropane, glycerin, pentaerythritol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, spiroglycol, tricyclodecanediol, tricyclodecanedimethanol, m-xylene glycol, o-xylene glycol, 1,4-phenylene glycol, bisphenol A, lactone polyester and polyols. A resin obtained by capping the polar group in the end of the polymer chain using an ordinary compound capable of capping an end may also be used.
Block copolyester resin components are also useful, and can be prepared by the transesterification of (a) straight or branched chain poly(alkylene terephthalate) and (b) a copolyester of a linear aliphatic dicarboxylic acid and, optionally, an aromatic dibasic acid such as terephthalic or isophthalic acid with one or more straight or branched chain dihydric aliphatic glycols. The polyesters are preferably a polyether ester block copolymer consisting of a thermoplastic polyester as the hard segment and a polyalkylene glycol as the soft segment.
The polyester can be present in the composition at about 1 to about 99 wt %, based on the total weight of the composition. Within this range, it is preferred to use at least about 25 wt %, more preferably at least about 30 wt % of the polyester. Preferred polyesters have an intrinsic viscosity (as measured in 60:40 solvent mixture of phenol/tetrachloroethane at 25° C.) ranging from about 0.1 to about 1.5 dL/g. Polyesters branched or unbranched and generally will have a weight average molecular weight of from about 5,000 to about 150,000, preferably from about 8,000 to about 95,000 as measured by gel permeation chromatography using 95:5 weight percent of chloroform:hexafluroisopropanol mixture. Other suitable materials include thermoplastic aliphatic and aromatic polycarbonates and copolymers thereof.
2) Polyester blends comprising polyamides having at least one terminal acid group, such as those comprising (A) about 99.98 to about 95 wt % of a polyester which comprises (1) a dicarboxylic acid component comprising repeat units from at least 85 mole percent terephthalic acid; and (2) a diol component repeat unit from at least 85 mole percent ethylene glycol, based on 100 mole percent dicarboxlic acid and 100 mole percent diol; and (B) a polyamide wherein at least 50% of the polyamide end groups are acid groups. The polyester (A), is typically selected from polyethylene terephthalate, polyethylene naphthalenedicarboxylate or copolyesters thereof. The acid component of polyester (A) contains repeat units from at least about 80 mole percent terephthalic acid, naphthlenedicarboxylic acid or mixtures thereof and at least about 85 mole percent ethylene glycol, based on 100 mole percent dicarboxylic acid and 100 mole percent diol.
3) Polyamides are another preferred intermediate cover layer material. Nylon 11, 12 and copolymers and toughened versions are also preferred, such as those disclosed in U.S. Pat. No. 6,800,690, the disclosure of which is incorporated herein in its entirety by reference thereto. Rigid grades of Pebax® poly(amide-ester or amide-ether) are also suitable materials. Other polymers include polyimides, polyether-ether ketones, and liquid crystalline polymers. Filled or reinforced versions of any of these materials are also suitable. Sorona®, commercially-available from DuPont, is another preferred intermediate cover layer material. DuPont Sorona® EP thermoplastic polymers contain between 20% and 37% renewably sourced material (by weight) derived from corn. The new material exhibits performance and molding characteristics similar to high-performance PBT (polybutylene terephthalate).
4) Compatibilized poly(arylene ether)/polyester compositions having stable phase morphology. The composition exhibits a unique combination of good heat resistance, dimensional stability, nominal strain at break and impact properties. Surprisingly it has been discovered that the amount of the disperse phase comprising poly(arylene ether) in relation to the amount of the total composition is critical to the formation of a stable morphology. The disperse phase comprising poly(arylene ether) is present in an amount that is less than or equal to 35 wt % based on the total weight of the composition. The impact modifier may reside in the disperse phase but may also be present at the interface between the phases. When the impact modifier resides in the disperse phase, the combined amount of impact modifier and poly(arylene ether) is less than 35 weight percent (wt %), based on the total weight of the composition. The exact amount and types or combinations of poly(arylene ether), impact modifier and polyester will depend, in part, on the requirements needed in the final blend composition. Most often, the poly(arylene ether) and impact modifier are present in an amount of 5 to 35 wt %, or, more specifically, 10 to 25 wt %, based on the total weight of the composition.
The poly(arylene ether) can comprise molecules having aminoalkyl-containing end group(s), typically located in an ortho position to the hydroxy group. Also frequently present are tetramethyl diphenylquinone end groups, typically obtained from reaction mixtures in which tetramethyl diphenylquinone by-product is present.
The poly(arylene ether) can be in the form of a homopolymer; a copolymer; a graft copolymer; an ionomer; or a block copolymer; as well as combinations comprising two or more of the foregoing polymers. Poly(arylene ether) includes polyphenylene ether comprising 2,6-dimethyl-1,4-phenylene ether units optionally in combination with 2,3,6-trimethyl-1,4-phenylene ether units.
At least a portion of the poly(arylene ether) is functionalized with a polyfunctional compound (functionalizing agent) such as a polycarboxylic acid or those compounds having in the molecule both (a) a carbon-carbon double bond or a carbon-carbon triple bond and b) at least one carboxylic acid, anhydride, amino, imide, hydroxy group or salts thereof. Examples of such polyfunctional compounds include maleic acid, maleic anhydride, fumaric acid, and citric acid. The poly(arylene ether) can be functionalized prior to making the composition or can be functionalized as part of making the composition. Furthermore, prior to functionalization the poly(arylene ether) can be extruded, for example to be formed into pellets. It is also possible for the poly(arylene ether) to be melt mixed with other additives that do not interfere with functionalization. Exemplary additives of this type include flame retardants, flow promoters, and the like.
In some embodiments the poly(arylene ether) can comprise 0.1 wt % to 90 wt % of structural units derived from a functionalizing agent. Within this range, the poly(arylene ether) can comprise less than or equal to 80 wt %, or, more specifically, less than or equal to 70 wt % of structural units derived from functionalizing agent, based on the total weight of the poly(arylene ether).
Examples of suitable polyesters are poly(allylene dicarboxylate)s, liquid crystalline polyesters, polyarylates, and polyester copolymers such as copolyestercarbonates and polyesteramides. Also included are polyesters that have been treated with relatively low levels of diepoxy or multi-epoxy compounds. It is also possible to use branched polyesters in which a branching agent, for example, a glycol having three or more hydroxyl groups or a trifunctional or multifunctional carboxylic acid has been incorporated. Treatment of the polyester with a trifunctional or multifunctional epoxy compound, for example, triglycidyl isocyanurate can also be used to make branched polyester. Furthermore, it is sometimes desirable to have various concentrations of acid and hydroxyl endgroups on the polyester, depending on the ultimate end-use of the composition.
Liquid crystalline polyesters having melting points less that 380° C. and comprising recurring units derived from aromatic diols, aliphatic or aromatic dicarboxylic acids, and aromatic hydroxy carboxylic acids are also useful. Mixtures of polyesters are also sometimes suitable.
The composition can comprise 40 to 90 wt % of the polyester, based on the total weight of the composition. Within this range the composition can comprise less than or equal to 80 wt %, or, more specifically, less than or equal to 75 wt %, or, even more specifically, less than or equal to 65 wt % polyester. Also within this range, the composition can comprise greater than or equal to 45 wt %, or, more specifically, greater than or equal to 50 wt % polyester.
The composition also comprises an impact modifier. In many embodiments the impact modifier resides primarily in the poly(arylene ether) phase. Examples of suitable impact modifiers include block copolymers; elastomers such as polybutadiene; random copolymers such as ethylene vinyl acetate; and combinations comprising two or more of the foregoing impact modifiers.
Exemplary block copolymers include A-B diblock copolymers and A-B-A triblock copolymers having one or two blocks A, which comprise structural units derived from an alkenyl aromatic monomer, for example styrene; and a rubber block, B, which generally comprises structural units derived from a diene such as isoprene or butadiene. The diene block may be partially hydrogenated. Mixtures of these diblock and triblock copolymers are especially useful.
Suitable A-B and A-B-A copolymers include, but are not limited to, polystyrene-polybutadiene; polystyrene-poly(ethylene-butylene); polystyrene-polyisoprene; polystyrene-poly(ethylene-propylene); poly(alpha-methylstyrene)-polybutadiene; poly(alpha-methylstyrene)-poly(ethylene-butylene); polystyrene-polybutadiene-polystyrene; polystyrene-poly(ethylene-butylene)-polystyrene; polystyrene-polyisoprene-polystyrene; polystyrene-poly(ethylene-propylene)-polystyrene; poly(alpha-methylstyrene)-polybutadiene-poly(alpha-methylstyrene); as well as selectively hydrogenated versions thereof, and the like, as well as combinations comprising two or more of the foregoing impact modifiers. Such A-B and A-B-A block copolymers are available commercially from a number of sources, including Phillips Petroleum under the trademark SOLPRENE, Kraton Polymers, under the trademark KRATON, Dexco under the trademark VECTOR, and Kuraray under the trademark SEPTON.
In addition to the poly(arylene ether), polyester, and impact modifier, the composition is made using a polymeric compatibilizer having an average of greater than or equal to 3 pendant epoxy groups per molecule. In some embodiments the polymeric compatibilizer has an average of at least 8 pendant epoxy groups per molecule.
Illustrative examples of suitable compatibilizers include, but are not limited to, copolymers of glycidyl methacrylate (GMA) with alkenes, copolymers of GMA with alkenes and acrylic esters, copolymers of GMA with alkenes and vinyl acetate, copolymers of GMA and styrene. Suitable alkenes comprise ethylene, propylene, and mixtures of two or more of the foregoing. Suitable acrylic esters comprise alkyl acrylate monomers, including, but not limited to, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, and combinations of the foregoing alkyl acrylate monomers. When present, the acrylic ester may be used in an amount of 15 wt % to 35 wt % based on the total amount of monomer used in the copolymer. When present, vinyl acetate may be used in an amount of 4 wt % to 10 wt % based on the total amount of monomer used in the copolymer. Illustrative examples of suitable compatibilizers comprise ethylene-glycidyl acrylate copolymers, ethylene-glycidyl methacrylate copolymers, ethylene-glycidyl methacrylate-vinyl acetate copolymers, ethylene-glycidyl methacrylate-alkyl acrylate copolymers, ethylene-glycidyl methacrylate-methyl acrylate copolymers, ethylene-glycidyl methacrylate-ethyl acrylate copolymers, and ethylene-glycidyl methacrylate-butyl acrylate copolymers;
5) Polycarbonate resins derived from bisphenol A and phosgene or a blend of two or more polycarbonate resins. The preferred polycarbonates are high molecular weight aromatic carbonate polymers have an intrinsic viscosity (as measured in methylene chloride at 25° C.) ranging from about 0.30 to about 1.00 dL/g. Polycarbonates may be branched or unbranched and generally will have a weight average molecular weight of from about 10,000 to about 200,000, preferably from about 20,000 to about 100,000 as measured by gel permeation chromatography. It is contemplated that the polycarbonate may have various known end groups. Other polycarbonates useful in the invention are disclosed in U.S. Pat. No. 7,345,116 which is incorporated herein in its entirety by reference thereto.
The preferred polycarbonates are preferably high molecular weight aromatic carbonate polymers have an intrinsic viscosity (as measured in methylene chloride at 25° C.) ranging from about 0.30 to about 1.00 dL/g. Polycarbonates may be branched or unbranched and generally will have a weight average molecular weight of from about 10,000 to about 200,000, preferably from about 20,000 to about 100,000 as measured by gel permeation chromatography. It is contemplated that the polycarbonate may have various known end groups. Typically such polyester resins include crystalline polyester resins such as polyester resins derived from an aliphatic or cycloaliphatic diol, or mixtures thereof, containing from about 2 to 20 carbon atoms and at least one aromatic dicarboxylic acid. Preferred polyesters are derived from an aliphatic diol and an aromatic dicarboxylic acid. The polyester resins are typically obtained through the condensation or ester interchange polymerization of the diol or diol equivalent component with the diacid or diacid chemical equivalent component.
Other preferred polycarbonates are disclosed in U.S. Patent Application Ser. No. 2007/0173618, the disclosure of which is incorporated herein in its entirety by reference thereto.
6) Polycarbonate/polyester blends, such as polymers including (A) about 1 to 99 wt % of at least one polycarbonate (A) comprising: (1) a diol component comprising about 90 to 100 mole percent 4,4′-isopropylidenediphenol residues, and (2) 0 to about 10 mole percent modifying diol residues, where the total mole percent of diol residues is equal to 100 mole percent; and (B) about 99 to 1 wt % of at least one polyester (B) comprising (1) diacid residues comprising about 70 to 100 mole percent dicarboxylic acid units, such as terephthalic acid residues, isophthalic acid residues, or mixtures thereof; and 0 to about 30 mole percent of modifying dicarboxylic acid residues, wherein the total mole percent of diacid residues is equal to 100 mole percent; and (2) diol residues comprising about 40 to 99.9 mole percent 1,4-cyclohexanedimethanol residues, 0.1 to about 60 mole percent neopentyl glycol residues, and 0 to about 10 mole percent modifying diol residues having 3 to 16 carbons, wherein the total mole percent of diol residues is equal to 100 mole percent; and wherein the total weight percent of said polycarbonate (A) and polyester (B) is equal to 100 weight percent.
The term “polyester,” as used herein, is intended to include “copolyesters” and is understood to mean a synthetic polymer prepared by the polycondensation of one or more difunctional carboxylic acids with one or more difunctional hydroxyl compounds. Typically the difunctional carboxylic acid is a dicarboxylic acid and the difunctional hydroxyl compound is a dihydric alcohol such as, for example, glycols and diols. The term “residue,” as used herein, means any organic structure incorporated into a polymer or plasticizer through a polycondensation reaction involving the corresponding monomer. The term “repeating unit,” as used herein, means an organic structure having a dicarboxylic acid residue and a diol residue bonded through a carbonyloxy group. Thus, the dicarboxylic acid residues may be derived from a dicarboxylic acid monomer or its associated acid halides, esters, salts, anhydrides, or mixtures thereof. As used herein, therefore, the term dicarboxylic acid is intended to include dicarboxylic acids and any derivative of a dicarboxylic acid, including its associated acid halides, esters, half-esters, salts, half-salts, anhydrides, mixed anhydrides, or mixtures thereof, useful in a polycondensation process with a diol to make a high molecular weight polyester.
Preferred polymer blends include at least one polyester(s) (B) comprising dicarboxylic acid residues, diol residues, and, optionally, branching monomer residues. The polyester(s) (B) included in the present invention contain substantially equal molar proportions of acid residues (100 mole %) and diol residues (100 mole %) which react in substantially equal proportions such that the total moles of repeating units is equal to 100 mole %. The mole percentages provided in the present disclosure, therefore, may be based on the total moles of acid residues, the total moles of diol residues, or the total moles of repeating units. For example, a polyester containing 20 mole % isophthalic acid, based on the total acid residues, means the polyester contains 20 mole % isophthalic acid residues out of a total of 100 mole % acid residues. Thus, there are 20 moles of isophthalic acid residues among every 100 moles of acid residues. In another example, a polyester containing 10 mole % ethylene glycol, based on the total diol residues, means the polyester contains 10 mole % ethylene glycol residues out of a total of 100 mole % diol residues. Thus, there are 10 moles of ethylene glycol residues among every 100 moles of diol residues.
Other polymer blends include polyester(s) (B) and polycarbonates (A) that are miscible and which typically exhibit only a glass transition temperature (T_g) as a blend, as measured by well-known techniques such as, for example, differential scanning calorimetry. The polyesters utilized in the present invention are amorphous or semi-crystalline and have glass transition temperatures of about 40 to 140° C., preferably about 60 to 100° C.
Suitable diacids include about 70 to 100 mole percent, preferably 80 to 100 mole percent, more preferably, 85 to 100 mole percent, even more preferably, 90 to 100 mole percent, and further 95 to 100 mole percent, of dicarboxylic acids, such as terephthalic acid residues, isophthalic acids, or mixtures thereof. The polyester may comprise about 70 to about 100 mole % of diacid residues from terephthalic acid and 0 to about 30 mole % diacid residues from isophthalic acid, alternatively about 0.1 to 30 mole percent isophthalic acid.
Polyester (B) may further include from about 0 to about 30 mole percent, preferably 0 to 10 mole percent, and more preferably, 0.1 to 10 mole percent of the residues of one or more modifying diacids (not terephthalic acid and/or isophthalic acid). Examples of modifying diacids containing that may be used include but are not limited to aliphatic dicarboxylic acids, alicyclic dicarboxylic acids, aromatic dicarboxylic acids, or mixtures of two or more of these acids. Specific examples of modifying dicarboxylic acids include, but are not limited to, one or more of succinic acid, glutaric acid, adipic acid, suberic acid, sebacic acid, azelaic acid, dimer acid, sulfoisophthalic acid. Additional examples of modifying diacids are fumaric, maleic, itaconic, 1,3-cyclohexanedicarboxylic, diglycolic, 2,5-norbornanedicarboxyclic, phthalic acid, diphenic, 4,4′-oxydibenzoic, and 4,4′-sulfonyldibenzoic. Other examples of modifying dicarboxylic acid residues include but are not limited to naphthalenedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid. Any of the various isomers of naphthalenedicarboxylic acid or mixtures of isomers may be used, but the 1,4-, 1,5-, 2,6-, and 2,7-isomers are preferred. Cycloaliphatic dicarboxylic acids such as, for example, 1,4-cyclohexanedicarboxylic acid may be present at the pure cis or trans isomer or as a mixture of cis and trans isomers. Dicarboxylic acids having 2 to 20 carbon atoms, preferably 2 to 18 carbon atoms, and more preferably, 2 to 16 carbon atoms, are included in one embodiment of the invention.
The polyester (B) also comprises diol residues that may comprise about 45 to about 95 mole percent of the residues of 1,4-cyclohexanedimethanol, 55 to about 5 mole percent of the residues of neopentyl glycol, and 0 to 10 mole percent of one or more modifying diol residues. As used herein, the term “diol” is synonymous with the term “glycol” and means any dihydric alcohol.
Alternatively, the blends typically include from about 1 to 99 weight percent, preferably 0.1 to 75 wt %, more preferably, 0.1 to 50 wt %, preferably 10 to 30 wt %, preferably 15 to 30 wt %, of at least one polycarbonate (A) comprising: (1) a diol component comprising about 90 to 100 mole percent 4,4′-isopropylidenediphenol residues; and (2) about 0 to 10 mole percent modifying diol residues; wherein the total mole percent of the diol residues is equal to 100 mole percent; and comprise from about 99 to 1 weight percent, preferably 99.9 to 25 weight percent, more preferably, 0.99.9 to 50 weight percent, and even more preferably, 75 to 50 weight percent of at least one polyester (B), wherein the total weight percent of polycarbonate (A) and polyester (B) is equal to 100 weight percent.
Suitable polycarbonates are typically derived from bisphenol A. Examples of suitable bisphenol A polycarbonates include the materials marketed under the tradenames LEXAN, available from the General Electric Company, and MAKROLON 2608, available from Bayer, Inc. The polycarbonate portion of the blends preferably has a diol component containing about 90 to 100 mole percent bisphenol A units, and 0 to about 10 mole percent can be substituted with units of other modifying aliphatic or aromatic diols, besides bisphenol A, having from 2 to 16 carbons. The polycarbonate can contain branching agents, such as tetraphenolic compounds, tri-(4-hydroxyphenyl) ethane, and pentaerythritol triacrylate. It is preferable to have at least 95 mole percent of diol units in the polycarbonate being bisphenol A.
Exemplary polyisocyanates suitable for use in the outer cover layer of the invention include, but are not limited to, 4,4′-diphenylmethane diisocyanate (MDI); polymeric MDI; carbodiimide-modified liquid MDI; 4,4′-dicyclohexylmethane diisocyanate (H12MDI); p-phenylene diisocyanate (PPDI); m-phenylene diisocyanate (MPDI); toluene diisocyanate (TDI); 3,3′-dimethyl-4,4′-biphenylene diisocyanate; isophoronediisocyanate; 1,6-hexamethylene diisocyanate (HDI); naphthalene diisocyanate; xylene diisocyanate; p-tetramethylxylene diisocyanate; m-tetramethylxylene diisocyanate; ethylene diisocyanate; propylene-1,2-diisocyanate; tetramethylene-1,4-diisocyanate; cyclohexyl diisocyanate; dodecane-1,12-diisocyanate; cyclobutane-1,3-diisocyanate; cyclohexane-1,3-diisocyanate; cyclohexane-1,4-diisocyanate; 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane; methyl cyclohexylene diisocyanate; triisocyanate of HDI; triisocyanate of 2,4,4-trimethyl-1,6-hexane diisocyanate; tetracene diisocyanate; napthalene diisocyanate; anthracene diisocyanate; isocyanurate of toluene diisocyanate; uretdione of hexamethylene diisocyanate; and mixtures thereof. Polyisocyanates are known to those of ordinary skill in the art as having more than one isocyanate group, e.g., di-isocyanate, tri-isocyanate, and tetra-isocyanate. Preferably, the polyisocyanate includes MDI, PPDI, TDI, or a mixture thereof, and more preferably, the polyisocyanate includes MDI. It should be understood that, as used herein, the term MDI includes 4,4′-diphenylmethane diisocyanate, polymeric MDI, carbodiimide-modified liquid MDI, and mixtures thereof and, additionally, that the diisocyanate employed may be “low free monomer,” understood by one of ordinary skill in the art to have lower levels of “free” monomer isocyanate groups, typically less than about 0.1% free monomer isocyanate groups.
When formed, polyurea prepolymers may contain about 10 percent to about 20 percent by weight of the prepolymer of free isocyanate monomer. Thus, in one embodiment, the polyurea prepolymer may be stripped of the free isocyanate monomer. For example, after stripping, the prepolymer may contain about 1 percent or less free isocyanate monomer. In another embodiment, the prepolymer contains about 0.5 percent by weight or less of free isocyanate monomer.
The polyether amine may be blended with additional polyols to formulate copolymers that are reacted with excess isocyanate to form the polyurea prepolymer. In one embodiment, less than about 30 percent polyol by weight of the copolymer is blended with the saturated polyether amine. In another embodiment, less than about 20 percent polyol by weight of the copolymer, preferably less than about 15 percent by weight of the copolymer, is blended with the polyether amine. The polyols listed above with respect to the polyurethane prepolymer, e.g., polyether polyols, polycaprolactone polyols, polyester polyols, polycarbonate polyols, hydrocarbon polyols, other polyols, and mixtures thereof, are also suitable for blending with the polyether amine. The molecular weight of these polymers may be from about 200 to about 4000, but also may be from about 1000 to about 3000, and more preferably are from about 1500 to about 2500.
The polyurea composition can be formed by crosslinking the polyurea prepolymer with a single curing agent or a blend of curing agents. The curing agent of the invention is preferably an amine-terminated curing agent, more preferably a secondary diamine curing agent so that the composition contains only urea linkages. In one embodiment, the amine-terminated curing agent may have a molecular weight of about 64 or greater. In another embodiment, the molecular weight of the amine-curing agent is about 2000 or less. As discussed above, certain amine-terminated curing agents may be modified with a compatible amine-terminated freezing point depressing agent or mixture of compatible freezing point depressing agents.
Suitable amine-terminated curing agents include, but are not limited to, ethylene diamine; hexamethylene diamine; 1-methyl-2,6-cyclohexyl diamine; tetrahydroxypropylene ethylene diamine; 2,2,4- and 2,4,4-trimethyl-1,6-hexanediamine; 4,4′-bis-(sec-butylamino)-dicyclohexylmethane; 1,4-bis-(sec-butylamino)-cyclohexane; 1,2-bis-(sec-butylamino)-cyclohexane; derivatives of 4,4′-bis-(sec-butylamino)-dicyclohexylmethane; 4,4′-dicyclohexylmethane diamine; 1,4-cyclohexane-bis-(methylamine); 1,3-cyclohexane-bis-(methylamine); diethylene glycol di-(aminopropyl) ether; 2-methylpentamethylene-diamine; diaminocyclohexane; diethylene triamine; triethylene tetramine; tetraethylene pentamine; propylene diamine; 1,3-diaminopropane; dimethylamino propylamine; diethylamino propylamine; dipropylene triamine; imido-bis-propylamine; monoethanolamine, diethanolamine; triethanolamine; monoisopropanolamine, diisopropanolamine; isophoronediamine; 4,4′-methylenebis-(2-chloroaniline); 3,5;dimethylthio-2,4-toluenediamine; 3,5-dimethylthio-2,6-toluenediamine; 3,5-diethylthio-2,4-toluenediamine; 3,5;diethylthio-2,6-toluenediamine; 4,4′-bis-(sec-butylamino)-diphenylmethane and derivatives thereof; 1,4-bis-(sec-butylamino)-benzene; 1,2-bis-(sec-butylamino)-benzene; N,N′-dialkylamino-diphenylmethane; N,N,N′,N′-tetrakis (2-hydroxypropyl) ethylene diamine; trimethyleneglycol-di-p-aminobenzoate; polytetramethyleneoxide-di-p-aminobenzoate; 4,4′-methylenebis-(3-chloro-2,6-diethyleneaniline); 4,4′-methylenebis-(2,6-diethylaniline); meta-phenylenediamine; paraphenylenediamine; and mixtures thereof. In one embodiment, the amine-terminated curing agent is 4,4′-bis-(sec-butylamino)-dicyclohexylmethane.
Suitable saturated amine-terminated curing agents include, but are not limited to, ethylene diamine; hexamethylene diamine; 1-methyl-2,6-cyclohexyl diamine; tetrahydroxypropylene ethylene diamine; 2,2,4- and 2,4,4-trimethyl-1,6-hexanediamine; 4,4′-bis-(sec-butylamino)-dicyclohexylmethane; 1,4-bis-(sec-butylamino)-cyclohexane; 1,2-bis-(sec-butylamino)-cyclohexane; derivatives of 4,4′-bis-(sec-butylamino)-dicyclohexylmethane; 4,4′-dicyclohexylmethane diamine; 4,4′-methylenebis-(2,6-diethylaminocyclohexane; 1,4-cyclohexane-bis-(methylannine); 1,3-cyclohexane-bis-(methylamine); diethylene glycol di-(aminopropyl) ether; 2-methylpentamethylene-diamine; diaminocyclohexane; diethylene triamine; triethylene tetramine; tetraethylene pentamine; propylene diamine; 1,3-diaminopropane; dimethylamino propylamine; diethylamino propylamine; imido-bis-propylamine; monoethanolamine, diethanolamine; triethanolamine; monoisopropanolamine, diisopropanolamine; isophoronediamine; triisopropanolamine; and mixtures thereof. In addition, any of the polyether amines listed above may be used as curing agents to react with the polyurea prepolymers.
Any method known to one of ordinary skill in the art may be used to combine the polyisocyanate, polyol, and curing agent of the present invention. One commonly employed method, known in the art as a one-shot method, involves concurrent mixing of the polyisocyanate, polyol, and curing agent. This method results in a mixture that is inhomogenous (more random) and affords the manufacturer less control over the molecular structure of the resultant composition. A preferred method of mixing is known as a prepolymer method. In this method, the polyisocyanate and the polyol are mixed separately prior to addition of the curing agent. This method affords a more homogeneous mixture resulting in a more consistent polymer composition.
Due to the very thin nature, it has been found by the present invention that the use of a castable, reactive material, which is applied in a fluid form, makes it possible to obtain very thin outer cover layers on golf balls. Specifically, it has been found that castable, reactive liquids, which react to form a urethane elastomer material, provide desirable very thin outer cover layers.
The castable, reactive liquid employed to form the urethane elastomer material can be applied over the core using a variety of application techniques such as spraying, dipping, spin coating, or flow coating methods which are well known in the art. An example of a suitable coating technique is that which is disclosed in U.S. Pat. No. 5,733,428, the disclosure of which is hereby incorporated by reference in its entirety by reference thereto.
The outer cover is preferably formed around the core and intermediate cover layers by mixing and introducing the material in the mold halves. It is important that the viscosity be measured over time, so that the subsequent steps of filling each mold half, introducing the core into one half and closing the mold can be properly timed for accomplishing centering of the core cover halves fusion and achieving overall uniformity. Suitable viscosity range of the curing urethane mix for introducing cores into the mold halves is determined to be approximately between about 2,000 cP and about 30,000 cP, with the preferred range of about 8,000 cP to about 15,000 cP.
To start the outer cover formation, mixing of the prepolymer and curative is accomplished in a motorized mixer including mixing head by feeding through lines metered amounts of curative and prepolymer. Top preheated mold halves are filled and placed in fixture units using pins moving into holes in each mold. After the reacting materials have resided in top mold halves for about 40 to about 80 seconds, a core is lowered at a controlled speed into the gelling reacting mixture. At a later time, a bottom mold half or a series of bottom mold halves have similar mixture amounts introduced into the cavity.
A ball cup holds the ball core through reduced pressure (or partial vacuum). Upon location of the coated core in the halves of the mold after gelling for about 40 to about 80 seconds, the vacuum is released allowing core to be released. The mold halves, with core and solidified cover half thereon, are removed from the centering fixture unit, inverted and mated with other mold halves which, at an appropriate time earlier, have had a selected quantity of reacting polyurethane prepolymer and curing agent introduced therein to commence gelling.
Similarly, U.S. Pat. Nos. 5,006,297 and 5,334,673 both disclose suitable molding techniques which may be utilized to apply the castable reactive liquids employed in the present invention. Further, U.S. Pat. Nos. 6,180,040 and 6,180,722 disclose methods of preparing dual core golf balls. The disclosures of these patents are hereby incorporated by reference in their entirety.
Other methods of molding include reaction injection molding (RIM) where two liquid components are injected into a mold holding a pre-positioned core. The liquid components react to form a solid, thermoset polymeric composition, typically a polyurethane or polyurea.
An optional filler component may be chosen to impart additional density to blends of the previously described components. The selection of such filler(s) is dependent upon the type of golf ball desired (i.e., one-piece, two-piece multi-component, or wound). Examples of useful fillers include zinc oxide, barium sulfate, calcium oxide, calcium carbonate and silica, as well as the other well known corresponding salts and oxides thereof. Additives, such as nanoparticles, glass spheres, and various metals, such as titanium and tungsten, can be added to the polyurethane compositions of the present invention, in amounts as needed, for their well-known purposes. Additional components which can be added to the polyurethane composition include UV stabilizers and other dyes, as well as optical brighteners and fluorescent pigments and dyes. Such additional ingredients may be added in any amounts that will achieve their desired purpose.
The golf balls of the present invention typically have a COR of greater than about 0.775, preferably greater than about 0.795, and more preferably greater than about 0.800. The golf balls also typically have an Atti compression of at least about 40, preferably from about 50 to 120, and more preferably from about 60 to 110. As used herein, the term “Atti compression” is defined as the deflection of an object or material relative to the deflection of a calibrated spring, as measured with an Atti Compression Gauge, that is commercially available from Atti Engineering Corp. of Union City, N.J. Atti compression is typically used to measure the compression of a golf ball. When the Atti Gauge is used to measure cores having a diameter of less than 1.680 inches, it should be understood that a metallic or other suitable shim is used to normalize the diameter of the measured object to 1.680 inches.
It should be understood that there is a fundamental difference between ‘material hardness’ and ‘hardness’ (as measured directly on a curved surface, such as a golf ball). Material hardness is defined by the procedure set forth in ASTM-D2240 and generally involves measuring the hardness of a flat “slab” or “button” formed of the material of which the hardness is to be measured. Hardness, when measured directly on a golf ball (or other spherical surface) is a different measurement and, therefore, many times produces a different hardness value. This difference results from a number of factors including, but not limited to, ball construction (i.e., core type, number of core and/or cover layers, etc.), ball (or sphere) diameter, and the material composition of adjacent layers (especially measuring soft, very thin layers over a layer from a harder material). It should also be understood that the two measurement techniques are not linearly related and, therefore, one hardness value cannot easily be correlated to the other. As used herein, the term “hardness” refers to hardness measured on the curved surface of the layer being measured (i.e., sphere including core+inner cover, sphere including core+inner cover+intermediate cover, or sphere including core+inner cover+intermediate cover+outer cover).
The core of the present invention has an Atti compression of between about 50 and about 90, more preferably, between about 60 and about 85, and most preferably, between about 70 and about 80. The outer diameter of the core is about 1.45 inches to 1.58 inches, more preferably about 1.50 inches to 1.56 inches, most preferably about 1.51 inches to 1.55 inches.
The thickness of the inner cover layer is preferably about 0.010 inches to 0.075 inches, more preferably about 0.030 inches to 0.060 inches, most preferably about 0.035 inches to 0.050 inches.
The thickness of the intermediate cover layer is preferably about 0.010 inches to 0.075 inches, more preferably about 0.030 inches to 0.060 inches, most preferably about 0.035 inches to 0.050 inches. In one alternative preferred embodiment, the thickness of the intermediate cover layer is about 0.015 inches to 0.030 inches.
The thickness of the outer cover layer is preferably about 0.005 inches to 0.045 inches, more preferably about 0.020 inches to 0.040 inches, and most preferably about 0.025 inches to 0.035 inches.
The flexural modulus of the intermediate layer on the golf balls, as measured by ASTM method D6272-98, Procedure B, is typically greater than about 55,000 psi, and is preferably from about 60,000 psi to 120,000 psi. Preferably, the intermediate layer compositions of the invention have a higher flexural modulus at a particular hardness than the inner cover layer ionomeric materials at the same hardness.
The golf ball can have an overall diameter of any size. While the United States Golf Association limits the minimum size of a golf ball to 1.680 inches, there is no maximum diameter. The golf ball diameter is preferably about 1.68 inches to 1.74 inches, more preferably about 1.68 inches to about 110 inches, and most preferably about 1.68 inches.
While any of the embodiments herein may have any known dimple number and pattern, a preferred number of dimples is 252 to 456, and more preferably is 330 to 392. The dimples may comprise any width, depth, and edge angle disclosed in the prior art and the patterns may comprises multitudes of dimples having different widths, depths and edge angles. Typical dimple coverage is greater than about 60%, preferably greater than about 65%, and more preferably greater than about 75%. The parting line configuration of said pattern may be either a straight line or a staggered wave parting line (SWPL). Most preferably the dimple number is 330, 332, or 392 and comprises 5 to 7 dimples sizes and the parting line is a SWPL.
Other than in the operating examples, or unless otherwise expressly specified, all of the numerical ranges, amounts, values and percentages such as those for amounts of materials and others in the specification may be read as if prefaced by the word “about” even though the term “about” may not expressly appear with the value, amount or range. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.
Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Furthermore, when numerical ranges of varying scope are set forth herein, it is contemplated that any combination of these values inclusive of the recited values may be used.
While it is apparent that the illustrative embodiments of the invention disclosed herein fulfill the objective stated above, it is appreciated that numerous modifications and other embodiments may be devised by those skilled in the art. Therefore, it will be understood that the appended claims are intended to cover all such modifications and embodiments, which would come within the spirit and scope of the present invention.

Claims

1. A golf ball comprising:

a core having a first shore D hardness;

an inner cover layer disposed about the core and the inner cover layer having a second Shore D hardness;

an intermediate layer about the inner cover layer and the intermediate layer having a third Shore D hardness;

an outer cover layer surrounding the intermediate layer; and

at least one of the inner cover layer or the intermediate layer formed of a rigid thermoplastic vulcanized composition formed from a reaction product of a rigid thermoplastic elastomer, at least one cross-linkable rubber in the presence of at least one initiator,

wherein a ratio of the second Shore D hardness to the third Shore hardness is between 0.70 to 0.97.

2. The golf ball of claim 1, wherein the inner cover layer is formed from the rigid thermoplastic vulcanized composition wherein the thermoplastic elastomer is selected from an aromatic copoly group consisting of ether-urethane or ether-urea or ester-urethane or ester-urea, or ether-ester-urethane or ether-ester-urea, or caprolactone-urethane or caprolactone-urea elastomers and their blends, the inner cover layer having a Shore D hardness of 55 to 65 and the intermediate layer being thermoplastic and including ionomers, or highly neutralized polymers, or non-ionomers having a shore D hardness of 60 to 75.

3. The golf ball of claim 1, wherein the inner cover layer is formed from the rigid thermoplastic vulcanized composition wherein the thermoplastic is selected from an aliphatic copoly group consisting of ether-urethane or ether-urea or ester-urethane or ester-urea, or ether-ester-urethane or ether-ester-urea, or caprolactone-urethane or caprolactone-urea elastomers and their blends, the inner cover layer having a Shore D hardness of 55 to 65 and the intermediate layer being thermoplastic including ionomers, or highly neutralized polymers, or non-ionomers having a shore D hardness of 60 to 75.

4. The golf ball of claim 1, wherein the inner cover layer is formed from the rigid thermoplastic vulcanized composition wherein the thermoplastic elastomer is selected from a copoly group consisting of ether-amide or ester-amide or ether-ester-amide elastomers and their blends having a Shore D hardness of 55 to 65 and the intermediate layer being a thermoplastic including ionomers, or highly neutralized polymers, or non-ionomers and having a shore D hardness of 60 to 75.

5. The golf ball of claim 1, wherein the intermediate layer is formed from the thermoplastic vulcanized composition wherein the thermoplastic elastomer is selected from an aromatic copoly group consisting of ether-urethane or ether-urea or ester-urethane or ester-urea, or ether-ester-urethane or ether-ester-urea, or caprolactone-urethane or caprolactone-urea elastomers and their blends having a Shore D hardness of 60 to 75 and the inner cover layer being a thermoplastic including ionomers, or highly neutralized polymers, or non-ionomers and having a shore D hardness of 55 to 65 and a flexural modulus of 50 to 60 kpsi.

6. The golf ball of claim 1, wherein the intermediate layer is formed from the thermoplastic vulcanized composition wherein the thermoplastic elastomer is selected from an aliphatic copoly group consisting of ether-urethane or ether-urea or ester-urethane or ester-urea, or ether-ester-urethane or ether-ester-urea, caprolactone-urethane or caprolactone-urea elastomers and their blends having a Shore D hardness of 60 to 75 and the inner cover layer being a thermoplastic including ionomers, or highly neutralized polymers, or non-ionomers and having a shore D hardness of 55 to 65 and a flexural modulus of 50 to 60 kpsi.

7. The golf ball of claim 1, wherein the intermediate layer is formed from the thermoplastic vulcanized composition wherein the thermoplastic elastomer is selected from a copoly group consisting of ether-amide or ester-amide or ether-ester-amide elastomers and their blends having a Shore D hardness of 60 to 75 and the inner cover layer being thermoplastic including ionomers, or highly neutralized polymers, or non-ionomers and having a shore D hardness of 55 to 65 and a flexural modulus of 50 to 60 kpsi.

8. The golf ball of claim 1, wherein both the inner cover layer and the intermediate layers are formed from the thermoplastic vulcanized composition wherein the thermoplastic elastomer is selected from an aromatic copoly group consisting of ether-urethane or ether-urea or ester-urethane or ester-urea, or ether-ester-urethane or ether-ester-urea, or caprolactone-urethane or caprolactone-urea elastomers and their blends, with the inner cover layer having a Shore D hardness or about 45 to 70 and a flexural modulus of about 30 to 80 kpsi, and the intermediate layer having a Shore D hardness of about 50 to 75 and a flexural modulus of about 40 to 100 kpsi.

9. The golf ball of claim 1, wherein both the inner cover layer and the intermediate layers are formed from the thermoplastic vulcanized composition wherein the thermoplastic elastomer is selected from an aliphatic copoly group consisting of ether-urethane or ether-urea or ester-urethane or ester-urea, or ether-ester-urethane or ether-ester-urea, or caprolactone-urethane or caprolactone-urea elastomers and their blends, with the inner cover layer having a Shore D hardness or about 45 to 70 and a flexural modulus of about 30 to 80 kpsi, and the intermediate layer having a Shore D hardness of about 50 to 75 and a flexural modulus of about 40 to 100 kpsi.

10. The golf ball of claim 1, wherein both the inner cover layer and the intermediate layers are formed from the thermoplastic vulcanized composition wherein the thermoplastic elastomer is selected from the copoly group consisting of ether-amide or ester-amide or ether-ester-amide elastomers and their blends with the inner cover layer having a Shore D hardness or about 45 to 70 and a flexural modulus of about 30 to 80 kpsi, and the intermediate layer having a Shore D hardness of about 50 to 75 and a flexural modulus of about 40 to 100 kpsi.

11. The golf ball of claim 1, wherein the ratio of the second Shore D hardness to the third being in the range of 0.75 to 0.95.

12. The golf ball of claim 1, wherein the ratio of the second Shore D hardness to the third being in the range of 0.80 to 0.92.

13. The golf ball of claim 1, wherein the cover layer is formed from a castable thermoset composition selected from a group consisting of polyurethane or polyurea or epoxy or cross-linkable rubber compositions, wherein the cover layer comprises a Shore D hardness of 40 to 60 and a flexural modulus of 15 to 45 kpsi.

14. The golf ball of claim 1, wherein the ball further includes a moisture barrier material having a moisture vapor transmission rate of 12.5 gmil/100 in.sup. 2/day or less about the inner cover layer or the intermediate to provide an improved shelf-life for the ball performance.

15. The golf ball of claim 1, wherein the core has a diameter of 0.70 to 1.58 inch.

16. The golf ball of claim 15 wherein the core has a diameter of 1.45 to 1.55 inch.

17. The golf ball of claim 1, wherein the inner cover layer has a thickness of about 0. 030 to 0.070 inch.

18. The golf ball of claim 17, wherein the inner cover layer has a thickness of about 0.030 to 0.050 inch.

19. The golf ball of claim 1, wherein the intermediate layer has a thickness of about 0.010 to 0.080 inch.

20. A golf ball comprising:

a core having a first shore D hardness;

an outer cover layer surrounding the intermediate layer; and

at least one of the inner cover layer or the intermediate layer formed of a rigid thermoplastic vulcanized composition formed from a reaction product of a rigid thermoplastic elastomer, at least one cross-linkable rubber in the presence of at least one initiator and an impact modifier (list form page 19),

wherein a ration of the second Shore D hardness to the third Shore hardness is between 0.70 to 0.97.