KR102408190B1 - Thermoplastic polymer composition containing highly neutralized low hardness and high resilience ethylene-unsaturated carboxylic acid copolymers with monofunctional aliphatic organic acid metal salt, and use thereof in the manufacture of golf balls - Google Patents

Abstract

The present invention relates to a thermoplastic polymer composition having high elasticity (high coefficient of restitution) and ductility (low hardness), a method for preparing the same, and its use as a golf ball component. In a specific embodiment, the present invention is an ethylene-(meth)acrylic acid copolymer, an acid anhydride group-containing polyolefin-based elastomer, after mixing an organic acid salt and a cation, the carboxylic acid group of the ethylene-(meth)acrylic acid copolymer is higher than 60% The present invention relates to a thermoplastic polymer composition or thermoplastic ionomer composition which has been converted into an ionomer neutralized to a neutral level but has excellent flowability and excellent melt processability as well as excellent physical properties of low hardness and high elasticity, a method for manufacturing the same, and its use in the manufacture of golf balls .

Description

A thermoplastic polymer composition comprising a highly neutralized low hardness high elasticity ethylene-unsaturated carboxylic acid copolymer and a monofunctional aliphatic organic acid metal salt, and its use in the manufacture of golf balls carboxylic acid copolymers with monofunctional aliphatic organic acid metal salt, and use thereof in the manufacture of golf balls}

The present invention relates to thermoplastic polymer compositions and their use in the manufacture of golf balls. More specifically, the present invention relates to a thermoplastic polymer composition comprising a copolymer of highly neutralized low hardness, high modulus ethylene and C ₃ -C ₈ α,β-ethylenically unsaturated carboxylic acid and a monofunctional aliphatic organic acid metal salt, and a golf ball production its use in

The latest high-end golf balls include three (3) piece, four (4) piece and multi-layer golf balls. A 'three-piece' golf ball typically includes a spherical rubber core, a mantle layer comprising a thermoplastic material formed thereon, and a thermoplastic or thermoset cover covering it. A 'two-piece' golf ball typically includes a spherical core and a thermoplastic material cover covering it. A 'multilayer' golf ball typically includes a spherical core, a cover, and one or more mantle layers present between the core and cover.

The cores of three-piece golf balls, two-piece golf balls and multi-layer golf balls have traditionally been made of thermosetting rubbers such as polybutadiene rubber. Manufacturing the core using thermoset rubber requires a complex multi-step process, and the scraps cannot be recycled.

One thermoplastic that has long proven useful in golf ball parts and other applications has been an ionomer of an alpha olefin, particularly ethylene and a C ₃ -C ₈ α,β-ethylenically unsaturated carboxylic acid copolymer. U.S. Patent No. 3,264,272 to Rees discloses a process for making ionomers from "direct" acid copolymers. A "direct" copolymer is a polymer polymerized by the simultaneous addition of all monomers, as opposed to graft copolymers made by grafting additional monomers onto an already made polymer, most commonly by free radical reaction. A method for making the acid copolymer that is the parent of the ionomer is described in US Pat. No. 4,351,931.

The acid copolymer may contain a third "softening" monomer that reduces the crystallinity of the polymer. Such acid copolymers wherein the alpha olefin is ethylene can be represented as E/X/Y copolymers, wherein E is ethylene and X is an α,β-ethylenically unsaturated carboxylic acid, in particular acrylic acid or methacrylic acid, Y is a softening comonomer. Preferred softening comonomers are C ₁ -C ₈ alkyl acrylates or methacrylate esters. X and Y can be present in a wide range of proportions, with X typically up to about 35% by weight of the polymer and Y typically up to about 50% by weight of the polymer.

Various cations capable of neutralizing acid groups in acid copolymers are known. It is known that the degree of neutralization can vary widely. Typical cations include lithium, sodium, potassium, magnesium, calcium, barium, lead, tin, zinc, aluminum, and combinations thereof. Although a degree of neutralization of 90% or more, and even close to 100%, is known, such a high degree of neutralization leads to loss of melt processability or physical properties such as extensibility and toughness. There is therefore a particular need for copolymers that have high acid levels and can be neutralized with cations other than barium, lead and tin.

Highly neutralized, low hardness, high modulus ionomer polymer compositions can be used as part of the mantle layer inside a golf ball because of their high elasticity. A golf ball made of a material in which the mantle layer has a high modulus of elasticity (repulsion) can fly a longer distance when struck with the same force. Most professional and amateur golfers want a golf ball that provides long distance on driver shots, control and stopping ability on full iron shots, as well as high spin on short "touch and feel" shots. The demand for materials for mantles is rapidly increasing because of the higher profitability of multi-layered golf balls with three or more pieces compared to two-piece golf balls.

These acid copolymers, wherein the alpha olefin is ethylene, containing a third "softening" monomer that reduces the crystallinity of the polymer, highly neutralizes the acid copolymer in which the E/X/Y copolymer contains an excess of organic acid (or salt). Korean Patent Publication No. 2002-0042870 discloses a thermoplastic plastic and a method for applying the same to a golf ball, and Dowsa's Surlyn HPF1000 and HPF 2000 are commercialized.

However, when applied to the three-piece or more multi-layered golf ball mantle layer, these materials have low hardness and excellent resilience, but are expensive (about 9.5 US $/kg). development and supply is required.

Accordingly, one object of the present invention is to provide a thermoplastic polymer composition suitable for manufacturing the mantle layer of a golf ball because it has low hardness and high rebound elasticity but is inexpensive in order to solve the problems associated with the prior art.

Another object of the present invention is to provide a golf ball mantle layer and a golf ball manufactured using the novel thermoplastic polymer composition described above.

Another object of the present invention is to provide a method for preparing the novel thermoplastic polymer composition described above.

In order to achieve one object of the present invention, one aspect of the present invention is

A thermoplastic polymer composition comprising:

(a) an ethylenically-unsaturated carboxylic acid copolymer, wherein the unsaturated carboxylic acid is a C ₃ to C ₈ α,β-ethylenically unsaturated carboxylic acid, the content of the carboxylic acid residues based on the weight of the copolymer 6 to 30% by weight of this ethylene-unsaturated carboxylic acid copolymer;

(b) at least one monofunctional aliphatic organic acid metal salt having less than 36 carbon atoms; and

(c) containing an acid anhydride group-containing polyolefin-based elastomer,

(a) the degree of neutralization of the carboxylic acid groups in the ethylene-unsaturated carboxylic acid copolymer in the form of a carboxylic acid base by means of a monovalent alkali metal cation or a divalent alkaline earth metal cation is at least 60% or more, the thermoplastic polymer composition provides

The thermoplastic polymer composition is prepared by adding the (c) acid anhydride group-containing polyolefin-based elastomer to the (a) ethylene-unsaturated carboxylic acid copolymer as a matrix to control melt processability and physical properties of the ionomer to neutralize higher than 60%. to reduce the hardness of the highly neutralized ionomer parenting the (a) copolymer to a degree, preferably to a degree of neutralization of almost 70%, more preferably a degree of neutralization of 90%, and to reduce the hardness of the (b) aliphatic organic acid in a sufficient amount By further adding a metal salt, the ion configuration in the ionomer using the copolymer (a) as a parent is effectively plasticized and/or the crystallinity of the ethylene residue block is significantly or completely suppressed.

In one embodiment of the present invention, the thermoplastic polymer composition may further include (d) a filler.

In one embodiment of the present invention, when the thermoplastic polymer composition is molded into a sphere having a diameter of 1.50 to 1.54 inches, the coefficient of restitution (COR) of the sphere is 0.790 or more, and the compressibility is 50 or less, ,

The coefficient of restitution is calculated by projecting the sphere at a rate of 125 feet/sec to a steel plate located 3 feet away from the initial velocity measurement point, and dividing the speed at which it bounces back from the steel plate divided by the initial velocity measured 3 feet away. value can be determined.

In one embodiment of the present invention, the degree of neutralization of the carboxylic acid groups in the (a) ethylene-unsaturated carboxylic acid copolymer is neutralized by a monovalent alkali metal cation or a divalent alkaline earth metal cation is 60 to 90% or Preferably, it may be 70% to 90%.

In one embodiment of the present invention, it is preferable that the unsaturated carboxylic acid in the (a) ethylene-unsaturated carboxylic acid copolymer is acrylic acid or methacrylic acid.

In one embodiment of the present invention, the (b) aliphatic organic acid metal salt is a metal salt of a C ₆ to C ₂₆ aliphatic organic acid, wherein the ion arrangement of the carboxylate group formed in the (a) ethylene-unsaturated carboxylic acid copolymer is It may be a non-volatile, immobile material that effectively plasticizes and/or inhibits the crystallinity of the block of ethylene residues. By modifying the ionomer of the (a) acid copolymer with a sufficient amount of the specific (b) aliphatic organic acid metal salt in a sufficient amount, the present inventors propose that the (a) acid copolymer without loss of processability such as flowability and physical properties such as extensibility and toughness was found to be able to neutralize to a high level. The (b) monofunctional aliphatic organic acid metal salt is a metal salt derived from at least one monofunctional aliphatic organic acid having less than 36 carbon atoms, in particular a C ₆ to C ₂₆ monofunctional aliphatic saturated or unsaturated organic acid, in particular, the ionic configuration is plasticized. It is a non-volatile, immobile organic acid salt capable of ionic array plasticizing or inhibiting the crystallinity of the ethylene residue block. Thus, by the action of the (b) monofunctional aliphatic organic acid metal salt to neutralize the carboxylic acid group in the copolymer (a) corresponding to the parent of the ionomer at a level higher than 60%, almost 70%, preferably 90% By adding a sufficient amount of cations to the (a) acid copolymer, it is possible to neutralize the acid copolymer at a high level without loss of processability such as flowability and physical properties such as extensibility and toughness.

In one embodiment of the present invention, the metal cation contained in the (b) aliphatic organic acid metal salt is at least one selected from the group consisting of lithium, sodium, potassium, rubidium, cesium, zinc, calcium, magnesium, barium, bismuth and strontium. may be a metal cation of

In one embodiment of the present invention, (c) the acid anhydride group-containing polyolefin-based elastomer is at least one selected from polyethylene-based elastomer, polypropylene-based elastomer and ethylene-vinyl acetate copolymer elastomer, and has 4 to 10 carbon atoms. It may be a polyolefin-based elastomer grafted with an acid anhydride.

In one embodiment of the present invention, the unsaturated dicarboxylic acid anhydride may be at least one selected from maleic anhydride, itaconic anhydride, and citraconic anhydride.

In one embodiment of the present invention, the acid anhydride group-containing polyolefin-based elastomer (c) may have an acid anhydride group grafting ratio of 0.1 to 10% by weight.

In one embodiment of the present invention, the filler may be at least one selected from zinc oxide, barium sulfate, tungsten carbide and tin oxide.

In order to achieve another object of the present invention, another aspect of the present invention is

The present invention provides a mantle for a three-piece or more multi-layered golf ball comprising the thermoplastic polymer composition according to an aspect of the present invention, and a golf ball comprising the mantle.

In order to achieve another object of the present invention, another aspect of the present invention is

As a method for preparing a thermoplastic polymer composition according to an aspect of the present invention,

(a) an ethylenically-unsaturated carboxylic acid copolymer, wherein the unsaturated carboxylic acid is a C ₃ to C ₈ α,β-ethylenically unsaturated carboxylic acid, the content of the carboxylic acid residues based on the weight of the copolymer 6 to 30% by weight of an ethylene-unsaturated carboxylic acid copolymer, (b) at least one monofunctional aliphatic organic acid metal salt having less than 36 carbon atoms, the ionomer formed from (a) the ethylene-unsaturated carboxylic acid copolymer An aliphatic organic acid metal salt, which is a non-volatile, non-mobile material in an amount that effectively plasticizes the ionic configuration of the carboxylate group formed therein and/or inhibits the crystallinity of the ethylene residue block, (c) the above (a) ethylenically-unsaturated carboxyl melt blending an acid anhydride group-containing polyolefin-based elastomer capable of reducing the hardness of the ionomer formed from the acid copolymer, and optionally (d) a filler; and

Simultaneously with or after the melt blending step, (a) the carboxylic acid groups in the ethylene-unsaturated carboxylic acid copolymer are neutralized in the form of carboxylate groups by a monovalent alkali metal cation or a divalent alkaline earth metal cation. A cation source is added in an amount sufficient to ensure that the degree of neutralization of the ionomer obtained is at least 60% and uniformly mixed to form (a) at least some of the carboxylic acid groups of the carboxylic acid groups in the ethylenically-unsaturated carboxylic acid copolymer. It provides a method for producing a thermoplastic polymer composition, comprising the step of converting into the ionomer by neutralizing with a valent alkali metal ion or a divalent alkaline earth metal ion.

That is, the preparation method according to another aspect of the present invention can effectively produce (a) an ethylene-unsaturated carboxylic acid copolymer (ie, an ionomer) having a degree of neutralization higher than 60%, particularly a copolymer having a degree of neutralization of nearly 70% to 90%. (a) a softening elastomer capable of lowering the hardness prior to neutralizing the copolymer to a high level, i.e., (c) an acid anhydride group-containing polyolefin-based elastomer; and (b) a monofunctional aliphatic organic acid metal salt in an amount sufficient to effectively plasticize the ionic configuration and/or significantly or completely inhibit the crystallinity of the block of ethylene residues in the (a) copolymer-parent ionomer. (a) incorporated into the copolymer. Through this, it is possible to obtain a thermoplastic polymer composition having an optimal balance of melt processability and physical properties.

The thermoplastic polymer composition according to the present invention may exhibit an optimal balance of melt processability and physical properties. The thermoplastic polymer composition according to the present invention has excellent flowability and excellent melt processability, and may have a COR of 0.790 or more and a compressibility of 50 or less when measured at an initial speed of 125 feet/sec. It is useful in the manufacture of molded articles such as spherical parts such as The thermoplastic polymer composition is particularly useful in the manufacture of three-piece and multi-layer golf balls.

Other basic features and advantages of the present invention will become apparent to those skilled in the art upon examination of the following detailed description, accompanying drawings, and appended claims for carrying out the following invention. However, the above detailed description, specific content for carrying out the invention and the accompanying drawings are only for illustrating the present invention and are not intended to limit the present invention:
1 is a photograph showing a cross-section of a mantle for a golf ball and a three-piece golf ball including the same according to an embodiment of the present invention.
Fig. 2 is an FT-IR chart of a low-hardness, high-elasticity ionomer (Example 4).
3 is a DSC chart of the low hardness and high elasticity ionomer (Example 4).
4 is a TGA chart of the low hardness and high elasticity ionomer (Example 4).

Hereinafter, the thermoplastic polymer composition according to the present invention, a method for preparing the same, and its use in the manufacture of golf balls will be described in more detail.

Hereinafter, "copolymer" as used herein refers to a polymer containing residues of two or more plural monomers. "(meth)acrylic acid" means methacrylic acid and/or acrylic acid.

Each component of the above-described thermoplastic polymer composition according to the present invention will be described in detail.

(a) Ethylene-unsaturated carboxylic acid copolymers and ionomers formed therefrom

In the present invention, the (a) ethylene-unsaturated carboxylic acid copolymer, which is the parent forming the ionomer, is preferably a "direct" acid copolymer. It is preferably a copolymer of an alpha olefin, in particular ethylene, with a C ₃ to C ₈ α,β-ethylenically unsaturated carboxylic acid, in particular acrylic acid or methacrylic acid.

Copolymers (a) wherein the alpha olefin is ethylene can be represented as E/X copolymers, wherein E is ethylene and X is said α,β-ethylenically unsaturated carboxylic acid. X preferably comprises from 6 to 30% by weight, preferably from 10 to 25% by weight and most preferably from 15 to 21% by weight, based on the weight of the copolymer (a).

Since the monomer and the polymer are prone to phase separation, it is difficult to prepare an ethylene-carboxylic acid copolymer having a high level of carboxylic acid (X) in a continuous polymerization reactor. However, this difficulty can be solved by using the "co-solvent technique" described in U.S. Patent No. 5,028,674 or by copolymerizing at a pressure somewhat higher than the pressure at which a copolymer with a lower carboxylic acid content is prepared. have.

(a) Examples of the copolymer include an ethylene-(meth)acrylic acid copolymer. (a) The content of the copolymer is 40 to 70% by weight based on the total weight of the thermoplastic polymer composition. (a) When the content of the copolymer is less than 40% by weight, the physical properties of the ionomer derived therefrom are not sufficient, and when it exceeds 70% by weight, there is a problem in that the hardness of the ionomer is excessively increased. (a) The content of the copolymer may be 50 to 65% by weight based on the total weight of the composition.

The content of the unsaturated carboxylic acid residue in the copolymer (a) may be 6 wt% to 20 wt%, preferably 9 to 15 wt%, based on the total weight of the copolymer (a). It is preferable that at least some of the carboxylic acid groups of the carboxylic acid groups in the unsaturated carboxylic acid residue are neutralized by a monovalent alkali metal ion or a divalent alkaline earth metal ion. That is, at least some of the carboxylic acid groups (-COOH) of the carboxylic acid groups are neutralized by a monovalent alkali metal cation or a divalent alkaline earth metal cation (for example, -COO ^- Na ⁺ or -COO ^- M ^2+- OOC- in the form of a salt). The degree of neutralization by cations such as monovalent alkali metal ions or divalent alkaline earth metal ions may be 60% or more, preferably 70% or more, and even about 90%. The (a) copolymer may be one type or two or more types. When the cation is added above the degree of neutralization, excellent mechanical properties can be obtained. The cation may be a cation of a monovalent alkali metal such as lithium, sodium, potassium, rubidium and cesium, and mixtures thereof, or a cation of a divalent alkaline earth metal such as beryllium, magnesium, calcium or mixtures thereof. Preferably, they are cations of monovalent alkali metals, such as lithium, sodium, potassium, rubidium, cesium, and mixtures thereof, More preferably, they are sodium, potassium, magnesium, and calcium cations. The cation is a cation of a monovalent alkali metal or a cation of a divalent alkaline earth metal and a compound containing an anion such as hydroxide, oxide, formate, acetate, carbonate, or mixtures thereof. The thermoplastic polymer composition of the present invention can be introduced into (a) The copolymer shows a mono-modal distribution showing one molecular weight peak in the molecular weight distribution curve.

The carboxylic acid groups in the ionomer from (a) copolymer may be at least partially or wholly ionized by a cation. The cation can form ionic crosslinks of the ionomer, and the strength of the thermoplastic polymer composition can be significantly increased according to the formation of the ionic crosslinks.

The ionomer component formed from the copolymer (a) present in the thermoplastic polymer composition of the present invention can be prepared, for example, from a copolymer or terpolymer of ethylene and an alpha-unsaturated or beta-unsaturated carboxylic acid. The copolymer (a) is formed by copolymerization of an olefin and an unsaturated carboxylic acid, the olefin may be ethylene or propylene, and the unsaturated carboxylic acid is an alpha-unsaturated carboxylic acid having 3 to 8 carbon atoms or a beta- It may be an unsaturated carboxylic acid, for example acrylic acid or methacrylic acid. In polymerizing the copolymer (a), an ester compound of an alpha-unsaturated or beta-unsaturated carboxylic acid other than the above-mentioned components may be used together. Unsaturated carboxylic acids are generally those having from 3 to 8 carbon atoms and may be, for example, acrylic acid or methacrylic acid. Typically, the copolymer (a) is prepared from 4 to 24 parts by weight of residues derived from acrylic acid or methacrylic acid, methyl acrylate, ethyl acrylate or butyl acrylate or vinyl acetate in 100 parts by weight of the copolymer (a). 0 to 40 parts by weight of residues derived from the residue, the remainder being residues derived from ethylene.

(b) monofunctional aliphatic organic acid metal salts

The organic acid salt used in the present invention is a monofunctional aliphatic saturated, unsaturated or polyunsaturated organic acid metal salt, in particular one or more organic acid metal salts having less than 36 carbon atoms. The metal salt may be various, in particular at least one selected from the group consisting of lithium salts, sodium salts, potassium salts, rubidium salts, cesium salts, zinc salts, calcium salts, magnesium salts, barium salts, bismuth salts and strontium salts of organic acids. It may be a metal salt.

(a) When the copolymer and the organic acid metal salt are melt-blended, it may be useful to use an organic acid metal salt having low volatility. Although an organic acid metal salt having a small number of carbon atoms may be used, it is preferably a non-volatile and non-mobile organic acid metal salt. (a) using an organic acid metal salt capable of effectively plasticizing the ionic configuration of a copolymer of ethylene and a C ₃ to C ₈ α,β-ethylenically unsaturated carboxylic acid or an ionomer thereof or reducing the crystallinity of the ethylene residue block; it is preferable "Non-volatile" means that (a) does not volatilize at the temperature of melt blending with the copolymer. "Non-migration" means that it does not migrate to the surface of a polymer and do not bloom under normal storage conditions (room temperature). Particularly useful organic acid metal salts include metal salts of less than C ₄ -C ₃₆ (eg C ₃₄ ), C ₆ -C ₂₆ , especially C ₆ -C ₁₈ organic acid. Organic acids particularly useful for forming organic acid metal salts include caproic acid, caprylic acid, capric acid, lauric acid, stearic acid, behenic acid, erucic acid, oleic acid and linoleic acid.

The content of the organic acid metal salt is 13 to 25% by weight based on the total weight of the composition. When the content of the organic acid salt is less than 13% by weight, (a) the copolymer is neutralized and does not significantly reduce the crystallinity of the ethylene residue block of the induced ionomer, so there is a problem in that the COR is lowered. When it exceeds 25 wt%, there is a problem in that the mechanical properties of the ionomer are deteriorated. More preferably, the content of the organic acid metal salt is 15 to 23 wt%.

(c) acid anhydride group-containing polyolefin-based elastomer

The thermoplastic polymer composition of the present invention includes (a) (c) an acid anhydride group-containing polyolefin-based elastomer for softening to lower the hardness of the ionomer of the ethylene-unsaturated carboxylic acid copolymer.

(c) the acid anhydride group-containing polyolefin-based elastomer is at least one selected from the aforementioned polyethylene-based elastomer, polypropylene-based elastomer, and ethylene-vinyl acetate copolymer elastomer, and is a polyolefin having 4 to 10 carbon atoms grafted with an unsaturated dicarboxylic acid anhydride. is an elastomer. (c) the acid anhydride group-containing polyolefin-based elastomer component may lower the hardness of the ionomer of the copolymer (a). The (c) acid anhydride group-containing polyolefin-based elastomer is obtained by grafting an acid anhydride to a polyolefin-based elastomer in a twin-screw extruder or a reaction vessel, and the acid anhydride group grafting ratio of the polyolefin-based elastomer is 0.1 to 10% by weight, preferably 0.5 to 5 % by weight.

The polyethylene-based elastomer is an ethylene-alpha-olefin copolymer elastomer containing ethylene as a main component, and more specifically, has an ethylene content of 70 to 95% by weight, and includes propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, It is an ethylene-alpha-olefin copolymer elastomer having an alpha-olefin content of 5 to 30% by weight, such as 1-octene, 1-nonene, 1-decene, 1-dodecene, and the like, and may be amorphous or nanocrystalline. For example, the polyethylene-based elastomer may be at least one selected from ethylene-octene, ethylene-hexene, and ethylene-butene. Specific examples of the polyethylene-based elastomer include: Engage 8200, an ethylene-octene-based elastomer, under the trade name Engage 8200 by Dow; and Dow's brand name Engage 7467, which is an ethylene-butene-based elastomer, and the like.

The polypropylene-based elastomer is a propylene-alpha-olefin copolymer elastomer containing propylene as a main component. More specifically, the propylene content is 70 to 95% by weight, and ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene , 1-octene, 1-nonene, 1-decene, 1-dodecene, etc. is a propylene-alpha-olefin copolymer elastomer having an alpha-olefin content of 5 to 30% by weight, and may be amorphous or nanocrystalline. Specific examples thereof include Vistamaxx Grade 2120, 2125, 2320, 2330, 3000, 3020FL, 3980FL, 6102FL, 6202, 6202FL, etc.; and Mitsui Chemicals' trade name Notio, Grade PN-2070, PN-3560, PN-0040, PN-2060, etc., which are propylene-1-butene copolymer elastomers.

More specific examples of the polyolefin-based elastomer may include an ethylene-vinyl acetate copolymer having a vinyl acetate content of 20% or more.

The acid anhydride used for preparing the polyolefin-based elastomer containing an acid anhydride group may be an unsaturated dicarboxylic acid anhydride having 4 to 10 carbon atoms, for example, maleic anhydride, itaconic anhydride, citraconic anhydride, etc. may be used, Maleic anhydride is most suitable, and the polyolefin-based elastomer containing an acid anhydride group is a polyolefin-based elastomer in which the above-described types of polyolefin-based elastomer and acid anhydride are kneaded in a twin-screw extruder or reaction vessel and subjected to graft reaction.

The content of the acid anhydride group-containing polyolefin-based elastomer may be 15 to 25 wt% based on the total weight of the composition. When the content of the acid anhydride group-containing polyolefin-based elastomer is less than 15% by weight, there is a problem in that the hardness of the composition increases, and when it is 25% by weight or more, the hardness of the composition decreases and the COR value decreases. More preferably, the content of the acid anhydride group-containing polyolefin-based elastomer is 17 to 22 wt%. For example, the acid anhydride group-containing polyolefin elastomer obtained from the twin-screw extruder is 0.1 to 10 parts by weight of an acid anhydride such as maleic anhydride, itaconic anhydride, citraconic anhydride, etc., preferably 0.2 to 100 parts by weight of the polyolefin-based elastomer 3 parts by weight, azo compounds such as 2,2-azobisisobutyronitrile and 2,2-azobis(2,4,4-trimethylvaleronitrile); Or 0.01 to 3 parts by weight, preferably 0.02 to 1 parts by weight, of a radical initiator such as peroxide such as dicumyl peroxide and t-butyl peroxide, and a graft reaction is performed through a twin-screw extruder (cylinder temperature; 180 to 250 ° C.) can be obtained by More specific examples of such an acid anhydride group-containing polyolefin-based elastomer include maleic anhydride graft polyolefin-based elastomers, such as Fusabond® N493 from Dow and Amplify GR 216 from Dow; and commercially sold by Mitsui Chemicals under the trade name Admer ^™ GT6E.

The acid anhydride group-containing polyolefin-based elastomer may preferably have a Showa hardness of 50A to 100A in terms of lowering the hardness of the thermoplastic polymer composition.

(d) fillers

The filler is an optional component selected to increase the density of the composition in order to improve the moment of inertia of the golf ball in consideration of the type of golf ball (three-piece or mantle layer) in the composition of the present invention. Generally, the filler is an inorganic material having a density greater than about 3 g/cc, preferably greater than 4 g/cc. Examples of useful fillers include zinc oxide, barium sulfate, tungsten carbide and tin oxide, as well as salts and oxides of zinc, barium, tungsten or tin. It is preferred that the filler is non-reactive or substantially non-reactive, does not enhance or increase hardness, and does not significantly reduce COR.

The content of the filler is 2 to 10% by weight based on the total weight of the composition. When the filler content is less than 2% by weight, the effect of increasing the density of the composition is not sufficient, and when it is 10% by weight or more, there is a problem in that the coefficient of restitution is rapidly lowered. More preferably, the filler content is 3 to 7% by weight.

The composition of the present invention may further include various additives as needed. Examples of such additives include antioxidants, processing aids such as fatty acid amides, light stabilizers, ultraviolet absorbers, pigments, dye materials, lubricants, antiblocking agents and/or crosslinking agents.

Low-hardness, high-elasticity thermoplastic material

The thermoplastic polymer composition according to an aspect of the present invention described above is a plastic material having ductility and a high coefficient of restitution (COR), that is, a high elasticity plastic material. When the thermoplastic polymer composition is molded into a sphere having a diameter of 1.50 to 1.54 inches, the coefficient of restitution (COR) of the sphere is 0.790 or more, and the compressibility is 50 or less. The coefficient of restitution was determined by projecting the sphere at a speed of 125 feet/sec to a steel plate located 3 feet away from the initial velocity measurement point, and measuring the rebound velocity from the steel plate 3 feet away. It is a value determined by dividing the initial speed.

This low-hardness, high-elasticity thermoplastic is preferably (a) an ethylene-unsaturated carboxylic acid copolymer, (b) at least one monofunctional aliphatic organic acid metal salt, (c) a polyolefin-based elastomer containing an acid anhydride group, and (d) a filler. is a melt-blended thermoplastic polymer composition. Preferably, (a) the carboxylic acid groups of the copolymer are 60% to 90% neutralized by the cation source. Preferably, (a) the carboxylic acid groups of the copolymer are neutralized using a cation source in an amount greater than that required to neutralize at least 60% of the carboxylic acid groups of the copolymer (a). Preferably, the cation source may be at least one alkali metal compound and alkaline earth metal compound selected from LiOH, KOH, NaOH, Mg(OH) ₂ , Li ₂ CO ₃ , K ₂ CO ₃ and Na ₂ CO ₃ . .

Mantle for golf ball and golf ball comprising same

The thermoplastic polymer composition of the present invention may be molded into injection molded articles and extrusion molded articles of various shapes, but in particular, it may be molded into a mantle for a golf ball and a golf ball including the same by using the good mechanical properties of low hardness and high elasticity described above. The thermoplastic polymer composition may be used alone or in combination with other polymers.

Accordingly, the mantle for a golf ball according to another aspect of the present invention includes the thermoplastic polymer composition according to one aspect of the present invention, that is, a low-hardness and high-elasticity thermoplastic plastic material. The mantle may be manufactured, for example, by injection molding the above-described low-hardness, high-elasticity thermoplastic plastic material onto a thermosetting rubber core of a three-piece or more golf ball.

A golf ball according to another aspect of the present invention includes the aforementioned mantle for a golf ball.

1 is a photograph showing a cross-section of a mantle for a golf ball and a three-piece golf ball including the same according to an embodiment of the present invention. Referring to FIG. 1 , the golf ball 100 includes a core 1 , a mantle layer 2 covering the core, and a cover 3 covering the mantle layer 2 .

Method for producing a highly neutralized, low-hardness, high-elasticity thermoplastic polymer composition with excellent melt processability

The highly neutralized low-hardness, high-elasticity thermoplastic polymer composition of the present invention having the above-mentioned constitution comprises the above-mentioned (a) ethylene-unsaturated carboxylic acid copolymer; (b) at least one monofunctional aliphatic organic acid metal salt having less than 36 carbon atoms, which effectively plasticizes the ionic configuration of the carboxylate group formed in the ionomer formed by neutralization thereof from the (a) ethylene-unsaturated carboxylic acid copolymer aliphatic organic acid metal salts, which are non-volatile, non-migrating substances in an amount to inhibit crystallinity and/or to inhibit crystallinity of the block of ethylene residues; (c) an acid anhydride group-containing polyolefin-based elastomer capable of reducing the hardness of the ionomer formed from the (a) ethylene-unsaturated carboxylic acid copolymer; and optionally (d) melt blending the filler; and

Simultaneously with or after the melt blending step, (a) the carboxylic acid groups in the ethylene-unsaturated carboxylic acid copolymer are neutralized in the form of carboxylate groups by a monovalent alkali metal cation or a divalent alkaline earth metal cation. A cation source is added in an amount sufficient to achieve a degree of neutralization of the ionomer obtained by at least 60% or more, preferably about 70%, more preferably about 90%, and uniformly mixed to obtain a degree of neutralization of the (a) ethylenically-unsaturated carbohydrate. It can be prepared by a method comprising the step of neutralizing at least some of the carboxylic acid groups of the carboxylic acid groups in the acid copolymer with a monovalent alkali metal ion or a divalent alkaline earth metal ion to convert to the ionomer.

The present inventors have found that this simultaneous or sequential neutralization of the copolymer (a) melt processability, such as flowability, without the use of an inert diluent; And it was found that, so as not to lose physical properties such as toughness and extensibility, it was found that (a) the only way to neutralize the copolymer at a level higher than the degree of neutralization in which melt processability and physical properties were lost when using the ionomer alone. That is, the inventors have found that (a) copolymers above 70%, preferably near 90%, without suffering the commonly encountered melt processability losses that may occur when (a) copolymers are neutralized to levels higher than 60%. % was found to be neutralized.

Melt blending (a) an ethylene-unsaturated carboxylic acid copolymer, (b) a monofunctional aliphatic organic acid metal salt, (c) an acid anhydride group-containing polyolefinic elastomer, and optionally (d) a filler is known in the art. It can be done in any way. For example, the components may be sufficiently homogeneously kneaded using a ribbon mixer, and melt blended in a twin screw extruder.

The prepolymer composition obtained by melt blending may be neutralized or further neutralized by methods known in the art. For example, when the prepolymer composition is kneaded with an alkali metal compound and an alkaline earth metal compound at an elevated temperature, for example, about 160 to 220° C., these compounds react with the carboxylic acid group of (a) the copolymer to neutralize it. . If necessary, kneading may be continued while further mixing the compound until a desired degree of neutralization is reached. This kneading is carried out at an elevated temperature, preferably in a molten state, and is continued until the alkali metal compound reacts substantially completely with the component (a) of the copolymer. Specifically, the (a) ethylene-unsaturated carboxylic acid copolymer in the thermoplastic polymer composition can be simultaneously neutralized using a SM Platex TEK 30 twin screw extruder. (a) According to the content level of the carboxylic acid group of the copolymer, the level of (b) monofunctional aliphatic organic acid metal salt for controlling the processability of the polymer composition may be adjusted within the above-described range. (a) As the content level of the carboxylic acid group in the main chain of the copolymer increases, it is necessary to increase the input ratio of the (b) aliphatic organic acid metal salt. (b) Specific examples of monofunctional aliphatic organic acid metal salts include hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, pentadecanoic acid, hexadecanoic acid, heptadeca metal salts such as oleic acid, octadecanoic acid (stearic acid), nonadecanoic acid and icosanoic acid or their corresponding monofunctional aliphatic organic acids containing at least one carbon-carbon double bond, preferably of which carbon atoms 10 or more nonvolatile nonionic substances, more preferably sodium stearate, zinc stearate, or magnesium stearate.

Finally, the obtained thermoplastic polymer composition may be directly subjected to, for example, an injection molding process, an extrusion molding process, or a blow molding process to be processed into an injection product such as a mantle for a golf ball, an extruded product, or the like.

Hereinafter, the present invention will be described in more detail by way of Examples and Comparative Examples. The following examples are merely illustrative to explain the present invention in more detail, and are not intended to limit the protection scope of the present invention.

Examples 1 to 4

The components shown in Table 1 below were weighed in the amounts shown in this table and put into a twin-screw extruder (32mm, L/D=40; manufacturer: SM Platex, product number: TEK 30). Among the ingredients listed in Table 1, the identity of the ingredients indicated by the brand name is as follows.

(1) ESCOR 5200: an ethylene-acrylic acid (E/AA) copolymer commercially available from Exxon Mobil (acrylic acid content of 15% by weight);

(2) Magnesium stearate (organic acid metal salt) purchased from Shinwon Chemical

(3) Adfin 130: an acid anhydride group-containing polyolefin-based elastomer commercially available from AM Solution;

(4) barium sulfate (filler) commercially available from Samchun Chemical;

(5) Magnesium hydroxide commercially available from Samchun Chemical as a cation source for neutralizing the carboxylic acid group of the ethylene-acrylic acid (E/AA) copolymer.

The number of each component in the table below indicates the weight percent of each component based on the total weight of the polymer composition.

A sufficient amount of magnesium hydroxide in a mixture of ethylene-acrylic acid (E/AA) copolymer (ESCOR 5200), Adfin130 and magnesium stearate while maintaining the shaft rotation speed of the twin-screw extruder in the range of about 300 to 400 rpm and the barrel temperature at about 190°C After adding, the barrel temperature of the twin-screw extruder was raised to about 200° C., and the reaction extrusion was performed while maintaining the shaft rotation speed at about 300 to 400 rpm to obtain polymer compositions 1 to 4 in Examples 1 to 4, respectively. At this time, it was added to this mixture to neutralize 70% and 80% or more of the carboxylic acid groups of the acrylic acid residues in the ethylene-acrylic acid (E/AA) copolymer (see Examples 1 and 2 in Table 1).

Table 1: Magnesium ionomer modified with ethylene-acrylic acid (E/AA) copolymer, magnesium stearate (organic acid metal salt), polyolefin-based elastomer mixture containing cation and acid anhydride.

Example ESCOR 5200
(weight%) Adfin
130
(weight%) type of cation organic acid metal salt
(weight%) sulfuric acid
barium
(weight%) neutralization degree
(%) melt index
(g/10min) One 56 21 Mg 20 3 70 0.8 2 56 21 Mg 20 3 80 0.6 3 53 21 Mg 23 3 70 1.0 4 53 21 Mg 23 3 80 0.7

Then, each of the thermoplastic polymer compositions 1 to 4 was prepared using a hot press to prepare a square-shaped specimen having a length of 100 mm, a width of 100 mm, and a thickness of 3 mm. Using this specimen, tensile strength at break, elongation at break, tensile strength at yield (tensile yield) and elongation yield) were determined according to ASTM D1708.

2-4 are FT-IR charts, DSC charts, and TGA charts, respectively, measured for 80% neutralized thermoplastic polymer composition 4 of Example 4; FT-IR was analyzed using PerkinElmer's Spectrum2 instrument, DSC was analyzed using TA's DSC250, and TGA was analyzed using HP-TGA7500 while raising the temperature by 10 degrees/min. The FT-IR chart shows that the acid groups of the ethylene-acrylic acid (E/AA) copolymer are highly neutralized with cations, and the DSC chart shows that the acid groups of the ethylene-acrylic acid (E/AA) copolymers are neutralized with cations to form ionomers. and the TGA chart shows that the highly neutralized, low-hardness, high-elasticity ionomer composition has excellent thermal stability.

The physical properties of the 80% neutralized thermoplastic polymer composition 4 of Example 4 are summarized in Table 2 below.

Hardness
(Shore D) COR Tensile strength at break (MPa) Yield tensile strength (MPa) Elongation at break (%) Elongation at yield
(%) 50 0.799 23.5 18.7 350 30

In Table 2, the coefficient of restitution (COR) is a value measured using a spherical specimen the size of a golf ball having a diameter of 1.52 inches obtained by molding using the thermoplastic polymer composition 4 under the injection molding conditions summarized in Table 3 below.

The coefficient of restitution was measured as follows. That is, the ball was fired using an air cannon at a speed of 125 feet/sec toward a steel plate located 3 feet away from the initial speed measurement point. After colliding with the steel plate, the rebound velocity was measured. The coefficient of restitution was determined by dividing this bounce rate by the initial rate.

Temperature (°C) cylinder rear 210 cylinder center 220 all cylinders 225 Nozzle 230 mold front/rear 10 melt molding material 195 Pressure (kg/cm ² ) 1st injection pressure 130 2nd injection pressure 110 Injection Hold 13 Molding cycle (sec) Pack 10 Hold pressure 480 Booster 10 Cure Time 15 Screw Retraction 5.4

Various physical properties required for the mantle for a golf ball were measured by using the spheres prepared using each of the polymer compositions 1 to 4 as a mantle. The results are summarized in Table 4 below.

Example 1 Example 2 Example 3 Example 4 Pore Size(in dia) 1.631 1.631 1.630 1.630 Equator Size(in dia) 1.631 1.631 1.630 1.630 Out of Round(in) 0.001 0.001 0.001 0.001 Compression (Instron) 45 45 43 43 Compression(Instron) Deformation amount 0.145 0.145 0.148 0.148 Weight(g) 42.24 42.28 42.16 42.18 COR (125 fps ball launch speed COR machine) 0.796 0.797 0.798 0.799

Referring to the results of Tables 2 and 4, the specimens obtained using the thermoplastic polymer compositions according to Examples 1 to 4 including all of the essential components of claim 1 had a coefficient of restitution (COR) much greater than 0.790 and compression ) is less than 50. From this, it can be seen that the thermoplastic polymer composition according to the present invention has low hardness and high rebound elasticity, but is suitable for manufacturing a three-piece or more multi-layered golf ball.

Claims (12)

A thermoplastic polymer composition comprising:
(a) an ethylenically-unsaturated carboxylic acid copolymer, wherein the unsaturated carboxylic acid is acrylic acid or methacrylic acid, the content of the carboxylic acid residue is 6 to 30% by weight based on the weight of the copolymer, and molecular weight distribution 50 to 65% by weight of one ethylene-unsaturated carboxylic acid copolymer exhibiting a mono-modal distribution showing one molecular weight peak in the curve;
(b) a monofunctional C ₆ to C ₂₆ aliphatic for plasticizing the ion configuration of the carboxylate group formed in the (a) ethylene-unsaturated carboxylic acid copolymer and/or suppressing the crystallinity of the ethylene residue block 13 to 25% by weight of an organic acid metal salt; and
(c) at least one polyolefin-based elastomer selected from polyethylene-based elastomer, polypropylene-based elastomer, and ethylene-vinyl acetate copolymer elastomer is at least one unsaturated dicarboxyl selected from maleic anhydride, itaconic anhydride and citraconic anhydride An acid anhydride group-containing polyolefin elastomer grafted with an acid anhydride, comprising: 15 to 25 wt% of an acid anhydride group-containing polyolefin-based elastomer having an acid anhydride group grafting ratio of 0.1 to 10 wt%; and
(d) 2 to 10% by weight of at least one filler selected from zinc oxide, barium sulfate, tungsten carbide, and tin oxide,
(a) the degree of neutralization in which the carboxylic acid groups in the ethylene-unsaturated carboxylic acid copolymer are neutralized in the form of a carboxylate group by a monovalent alkali metal cation or a divalent alkaline earth metal cation is at least 60%,
When the thermoplastic polymer composition is molded into a sphere having a diameter of 1.50 to 1.54 inches, the coefficient of restitution (COR) of the sphere is 0.790 or more, and the compressibility is 50 or less,
The coefficient of restitution was determined by projecting the sphere at a speed of 125 feet/sec to a steel plate located 3 feet away from the initial velocity measurement point, and measuring the rebound velocity from the steel plate 3 feet away. Thermoplastic polymer composition, characterized in that determined by dividing the initial velocity. The thermoplastic polymer composition of claim 1, wherein the monovalent alkali metal cation or divalent alkaline earth metal cation is lithium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, or a mixture thereof. The metal cation according to claim 1, wherein the metal cation contained in the (b) aliphatic organic acid metal salt is at least one metal cation selected from the group consisting of lithium, sodium, potassium, rubidium, cesium, zinc, calcium, magnesium, barium, bismuth and strontium. A thermoplastic polymer composition, characterized in that A golf ball comprising a mantle for a golf ball comprising the thermoplastic polymer composition according to claim 1 . A method for preparing a thermoplastic polymer composition according to any one of claims 1 to 3, comprising:
(a) an ethylenically-unsaturated carboxylic acid copolymer, wherein the unsaturated carboxylic acid is acrylic acid or methacrylic acid, the content of the carboxylic acid residue is 6 to 30% by weight based on the weight of the copolymer, and molecular weight distribution 50 to 65% by weight of an ethylene-unsaturated carboxylic acid copolymer exhibiting a mono-modal distribution showing one molecular weight peak in the curve, (b) an ionomer formed from the (a) ethylene-unsaturated carboxylic acid copolymer 13 to 25 wt% of a monofunctional C ₆ to C ₂₆ aliphatic organic acid metal salt for plasticizing the ionic configuration of the carboxylate group formed therein and/or suppressing the crystallinity of the ethylene residue block, (c) maleic anhydride; At least one polyolefin-based elastomer selected from a polyethylene-based elastomer, a polypropylene-based elastomer, and an ethylene-vinyl acetate copolymer elastomer, in which at least one unsaturated dicarboxylic acid anhydride selected from itaconic anhydride and citraconic anhydride is grafted An acid anhydride group-containing polyolefin-based elastomer, 15 to 25% by weight of an acid anhydride group-containing polyolefin-based elastomer having an acid anhydride group grafting ratio of 0.1 to 10% by weight, and (d) zinc oxide, barium sulfate, tungsten carbide and tin oxide melt blending 2 to 10 weight percent of at least one filler; and
Simultaneously with or after the melt blending step, (a) the carboxylic acid groups in the ethylene-unsaturated carboxylic acid copolymer are neutralized in the form of carboxylate groups by a monovalent alkali metal cation or a divalent alkaline earth metal cation. A cation source is added in an amount sufficient to provide a degree of neutralization of the ionomer obtained by at least 60% or more and uniformly mixed to form (a) at least some of the carboxylic acid groups of the carboxylic acid groups in the ethylenically-unsaturated carboxylic acid copolymer. A method for producing a thermoplastic polymer composition comprising the step of neutralizing with a monovalent alkali metal ion or a divalent alkaline earth metal ion to convert the ionomer into the ionomer. delete delete delete delete delete delete delete

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