JPH0873683A - Resin composition excellent in impact resistance and golf ball skin material - Google Patents

Abstract

(57) [Summary] [Object] To provide an ionomer resin composition useful as a golf ball skin material having high impact resilience and excellent impact resistance. [Structure] The unsaturated carboxylic acid content is 5 to 10 mol%,
6 of the carboxyl groups of the ethylene-unsaturated carboxylic acid copolymer having a melt flow rate of 110 to 500 g / 10 min.
It is obtained by neutralizing 0 to 80 mol% with a divalent metal ion and has a melt flow rate of at least 25% by weight or more of an ionomer resin of 0.1 to 5.0 g / 10 minutes and an unsaturated carboxylic acid content. Of 5 to 10 mol% of at least 20 of the carboxyl groups of the ethylene-unsaturated carboxylic acid copolymer
Bending rigidity obtained by neutralizing more than mol% with monovalent metal ions 2
An ionomer resin having 90 MPa or more is blended. [Effect] By using the ionomer resin composition of the present invention as the surface of a golf ball, it is possible to provide a ball having excellent flight distance and durability upon hitting.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an ionomer resin composition useful as a golf ball skin material. More specifically, it relates to a specific ionomer resin composition for a golf ball skin material, which has high impact resilience and is also excellent in impact resistance.

[0002]

2. Description of the Related Art Ionomer resins are often used as the surface material of conventional two-piece golf balls and some thread-wound golf balls. This is because the ionomer resin has excellent impact resilience, cut resistance and impact resistance, and is easy to process. Particularly, by melting and mixing the sodium ionomer excellent in impact resilience using sodium ion as a metal ion and the zinc ionomer excellent in impact resistance and cut resistance using zinc ion in an appropriate ratio, the sodium ionomer is more than the sodium ionomer itself. It is known that impact resilience is improved,
Golf balls using such a mixture of ionomer resins as a skin material have been proposed and widely used (US Pat. No. 3,819,768).

Generally, the performance required for a golf ball is flight distance, controllability, durability, feel at the time of hitting, etc., and among them, golfers particularly desire to extend the flight distance. As one method for extending the flight distance of a golf ball, it is known that it is effective to use a material having high impact resilience as a skin material, and thus far, it relates to an ionomer resin having high impact resilience and a mixture thereof. A number of patents have been proposed.

Japanese Patent Laid-Open No. 2-297383 discloses a golf ball skin material having excellent impact resilience, which comprises a lithium ion ionomer, which is superior in impact resilience as compared with a sodium ionomer, as a main component, and which has divalent or trivalent metal ions A mixture with an ionomer has been proposed. Furthermore, JP-A-2-149277 and JP-B-4-508.
Japanese Patent Laid-Open No. 33-33 proposes a golf ball skin material having a lithium ionomer as a component and excellent in impact resilience.

Further, Japanese Patent Laid-Open No. 3-207382 discloses that
As a golf ball skin material having excellent impact resilience, a flexural rigidity based on an ethylene-acrylic acid copolymer is 3
Alkali metal ion neutralized ionomer of 000 kg / cm ² (294 MPa) or more, and bending rigidity of 1500 kg
A mixture of divalent metal-neutralized ionomers having a viscosity of 1 / cm ² (147 MPa) or more has been proposed, and it is considered unsuitable if the flexural rigidity of the alkali metal ion-neutralized ionomer is less than 3000 kg / cm ² because the impact resilience is insufficient. Further, Japanese Patent Publication No. 4-49426 and Japanese Patent Laid-Open No. 2-2687.
Japanese Patent Laid-Open No. 79 proposes a golf ball skin material excellent in impact resilience using an ionomer of an ethylene-acrylic acid copolymer as at least one component.

Further, in JP-A-4-96772, an ethylene-unsaturated carboxylic acid copolymer having a high unsaturated carboxylic acid content of 16 to 30% by weight is neutralized with a monovalent or divalent metal ion. Made of ionomer resin in skin material 2
A golf ball having an excellent impact resilience, which is compounded in an amount of 0% by weight or more, has been proposed. Further, JP-A-6-114124 uses a mixture of two or more ionomers of an ethylene-unsaturated carboxylic acid copolymer having a high unsaturated carboxylic acid content of 18.5 to 21.5% by weight. A golf ball skin material having a high coefficient of restitution has been proposed.

[0007]

However, it is known that the ionomer resin tends to have higher hardness and rigidity as the impact resilience increases, while the impact resistance decreases as the hardness and rigidity increase. ing.

Therefore, the above-mentioned prior art is recognized as an effective method for improving the rebound resilience of a golf ball, but at the same time, the hardness and rigidity of the skin material increase, so that a golf ball using such a skin material will not fly. Although it satisfies the golfer's requirement to extend the distance, it also has the drawback of poor durability and impact resistance. It is presumed that the reason why the ionomer resin having high impact resilience and high rigidity has been practically used as a skin material of a golf ball is inferior in impact resistance.

The present inventors have found that a specific ionomer obtained by neutralizing an ethylene-unsaturated carboxylic acid copolymer having a relatively high melt flow rate with a divalent metal ion in a predetermined ratio and an ethylene-unsaturated carboxylic acid copolymer are used. By blending a specific ionomer having high impact resilience and high rigidity obtained by neutralizing the coalescence with monovalent metal ions in a predetermined ratio, impact resistance can be remarkably improved while having high impact resilience. I found it.

That is, an object of the present invention is to provide an ionomer resin composition useful as a golf ball skin material having high impact resilience and excellent impact resistance.

[0011]

According to the present invention, a resin composition comprising an ionomer resin neutralized with a divalent metal ion and an ionomer resin neutralized with a monovalent metal ion is unsaturated. 50-80 mol% of the carboxyl groups of the ethylene-unsaturated carboxylic acid copolymer having a carboxylic acid content of 5-10 mol% and a melt flow rate of 110-500 g / 10 min are neutralized with a divalent metal ion. And its melt flow rate is 0.1-5.0 g / 10
Of at least 25% by weight of the ionomer resin (A), and at least 20% by mole or more of the carboxyl groups of the ethylene-unsaturated carboxylic acid copolymer having an unsaturated carboxylic acid content of 5 to 10% by mole. Provided is a resin composition excellent in impact resilience and impact resistance, which is prepared by blending an ionomer resin (B) having a flexural rigidity of 290 MPa or more neutralized with metal ions.

According to the present invention, there is also provided a golf ball skin material comprising the above ionomer resin composition.

[0013]

In the present invention, a specific divalent metal ion neutralized ionomer, that is, an unsaturated carboxylic acid content of 5 to 10 mol% and a melt flow rate of 110 to 500 g / 10 min of ethylene-unsaturated carboxylic acid copolymer is used. An ionomer resin (A having a melt flow rate of 0.1 to 5.0 g / 10 min), which is obtained by neutralizing 60 to 80 mol% of the carboxyl groups of the combined product with a divalent metal ion, particularly zinc ion and magnesium ion. ) And a highly rigid specific monovalent metal ion neutralized ionomer, that is, an unsaturated carboxylic acid content of 5 to 1
Bending rigidity of 290 MPa in which at least 20 mol% or more of the carboxyl groups of 0 mol% of unsaturated carboxylic acid copolymer are neutralized with monovalent metal ions, particularly alkali metal ions
The ionomer resin (B) having the above is selected, and at least 25% by weight or more of the ionomer resin (A) is blended and combined to obtain a significantly improved impact resistance while having a high impact resilience. A resin composition for a golf ball skin material having the same can be obtained.

It is important to use a golf ball having a high rebound resilience as a golf ball skin material composed of an ionomer composition in order to extend the flight distance of a ball required by a golfer. On the other hand, a high rebound resilience ionomer composition is used. Generally has a tendency to have high hardness and rigidity, and such a skin material has a drawback that it has poor impact resistance.

In the present invention, the divalent metal ion-neutralized ionomer (A) of the above-mentioned specific ethylene-unsaturated carboxylic acid copolymer is selected, and this is used as an ethylene-union having a specific high impact resilience and high rigidity. By combining it with a monovalent metal ion neutralized ionomer of a saturated carboxylic acid copolymer, it has succeeded in significantly improving impact resistance while having high impact resilience. The importance of the above selections and combinations will be apparent with reference to Tables 1 and 2 in the examples below.

By using this composition as a golf ball skin material, a golf ball having high impact resilience and excellent impact resistance can be provided.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The ethylene-unsaturated carboxylic acid copolymer used in the present invention is a binary copolymer of ethylene and an unsaturated carboxylic acid, or ethylene, a (meth) acrylic acid ester and an unsaturated carboxylic acid. The terpolymer of is used.

As the unsaturated carboxylic acid, acrylic acid,
Ethylenically unsaturated carboxylic acids having 3 to 8 carbon atoms such as methacrylic acid, crotonic acid, maleic acid half ester, and fumaric acid half ester can be used.
Methacrylic acid is preferred.

This copolymer may contain a (meth) acrylic acid ester as a copolymerization component, and as the copolymerization component, for example, methyl (meth) acrylate,
Examples thereof include acrylic acid esters and methacrylic acid esters such as ethyl (meth) acrylate, n-butyl (meth) acrylate, and isobutyl (meth) acrylate.

The copolymerization ratio of such (meth) acrylic acid ester is preferably 0 to 10 mol%, particularly preferably 0 to 8 mol%. Further, this copolymer may be copolymerized with a small amount of other monomers such as styrene or vinyl acetate within a range not impairing the object of the present invention. Such a copolymer can be obtained by randomly copolymerizing each polymerization component under high temperature and high pressure.

As is already known, the ionomerization method is carried out by using the above-mentioned ethylene-unsaturated carboxylic acid copolymer as a metal hydroxide, oxide, carbonate, bicarbonate, acetate, alkoxide or the like. Depending on the method, there is a method of partially or completely neutralizing in a molten state or a state of being dissolved or suspended in a medium such as water.

In a preferred embodiment of the present invention, the divalent metal ion neutralized ionomer (A) of the ethylene-unsaturated carboxylic acid copolymer has an unsaturated carboxylic acid content of 5 to 10 mol%, preferably 5. 4-8.5 mol%, melt flow rate 110-500 g / 10 min, preferably 150
˜350 g / 10 min of the carboxyl group of the ethylene-unsaturated carboxylic acid copolymer, 60 to 80 mol%, preferably 65 to 80 mol% is selected from the group consisting of divalent metal ions, preferably zinc and magnesium. Neutralized with at least one divalent metal ion, particularly preferably zinc ion, having a melt flow rate of 0.1 to
5.0 g / 10 minutes, preferably 0.4-4.5 g / 10
It is better to use the minute ionomer.

When a copolymer having an unsaturated carboxylic acid content less than the above range is used, a composition having a high impact resilience cannot be obtained, and a copolymer having an unsaturated carboxylic acid content of more than 10 mol% is used. If so, the hygroscopicity is large and the impact resistance is lowered, which is not preferable.

One of ethylene-unsaturated carboxylic acid copolymers
Melt flow rate at 90 ° C and 2160 load is 1
If it is less than 10 g / 10 minutes, the flowability of the ionomer neutralized with metal ions in the molten state becomes too low, which hinders the moldability and also the melt flow rate of the ethylene-unsaturated carboxylic acid copolymer. If it is more than 500 g / 10 minutes, the impact resistance is inferior, which is not preferable.

When the degree of neutralization of the ethylene-unsaturated carboxylic acid copolymer with divalent metal ions is lower than 60 mol%, the impact resistance of the composition is not improved so much and the degree of neutralization is 80 mol%. If it is larger than the above range, the flowability of the ionomer in the molten state becomes too low, which impairs the moldability and is not preferable.

If the melt flow rate of the ionomer at 190 ° C. under a load of 2160 g is less than 0.1 g / 10 minutes, the fluidity in the molten state will be too low and the moldability will be impaired, and the melt flow rate will be 5. 0 g / 10
If it is larger than this, the effect of improving impact resistance is inferior, which is not preferable.

In a preferred embodiment of the present invention, the ethylene-unsaturated carboxylic acid copolymer monovalent metal ion neutralized ionomer (B) has an unsaturated carboxylic acid content of 5 to 10 mol%, preferably 5. At least 20 mol% or more, preferably 25 to 60 mol% of the carboxyl groups of the ethylene-unsaturated carboxylic acid copolymer of 4 to 8.5 mol% are monovalent metal ions, preferably alkalis of lithium, sodium and potassium. Flexural rigidity 290 MPa neutralized with ions of at least one metal selected from the group consisting of metals
Above, it is preferable to use an ionomer having preferably 300 MPa or more.

When a copolymer having an unsaturated carboxylic acid content of less than 5 mol% is used, a composition having a high impact resilience cannot be obtained, and a copolymer having an unsaturated carboxylic acid content of more than 10 mol% is used. If it is used, it is not preferable because it has high hygroscopicity and impact resistance decreases.

If the degree of neutralization and the flexural rigidity are lower than the above ranges, a composition having high impact resilience cannot be obtained, which is not preferable.

The monovalent metal ion-neutralized ionomer (B) has a melt flow rate of 0.1 to 30 g / 10 minutes, particularly 0.5 to 15 at 190 ° C. under a load of 2160 g.
It is preferably g / 10 minutes.

Composition of the divalent metal ion neutralized ionomer (A) of the ethylene-unsaturated carboxylic acid copolymer of the present invention and the monovalent metal ion neutralized ionomer (B) of the ethylene-unsaturated carboxylic acid copolymer. The product has at least 25 ionomers (A) when the total weight is 100% by weight.
It is preferable that the compounding amount is not less than wt%.

If the proportion of the ionomer (A) is less than the above range, the impact resistance improving effect is low, which is not preferable.

The composition of the present invention is prepared by mixing the ionomer (A) and the ionomer (B) with a single-screw or twin-screw extruder for plastic, or an intensive mixer such as a plastomill or a Banbury mixer.
It is obtained by melt-kneading at a temperature of 00 to 280 ° C.

The resin composition of the present invention may contain a small amount of another polymer as long as the object of the present invention is not impaired.
In addition, it goes without saying that various additives that are usually blended with the golf ball skin material may be blended. Examples of such additives include various colorants, inorganic fillers, antioxidants, weather resistance stabilizers and dispersants.
Typical additives are, for example, pigments such as titanium oxide, zinc oxide, barium sulfate and zinc zinc, and various dyes and pigments.

The skin made of the resin composition of the present invention can be used for coating any of known solid golf ball cores and thread wound golf ball cores. The solid core is obtained by heating (crosslinking) a rubber composition mainly composed of rubber and integrally molding the same, and the thread-wound core is obtained by winding a thread rubber around a core body.

The method of coating the core with the skin material is not particularly limited, and an ordinary method is used. For example, the ionomer resin composition according to the present invention, or a composition for a skin material in which other components are blended as necessary, is formed in advance into a hemispherical shell shape called a half shell, and two cores are used to wrap the core. A method of wrapping the core by pressure molding at 130 to 170 ° C. for 1 to 5 minutes or by directly injection molding the composition for skin material is used. The thickness of the epidermis is usually about 1.0 to 3.0 mm. Then, when forming the skin, dimples are formed on the surface of the ball as necessary, and the obtained ball is subjected to paint finishing, stamping or the like as necessary.

[0037]

The present invention will be described in more detail by way of examples. The ionomer resins used for preparing the composition of the present invention are shown in Table 1.

[0038]

[Table 1]

The test methods for measuring the physical properties of the composition and the raw materials are as follows. (1) Melt flow rate (MFR): JIS-K6760 compliant Temperature 190 ° C., load 2160 g (2) Tensile strength and elongation JIS-K6760 compliant 2 mm thick sheet hot-press molded at 180 ° C. was punched as a test piece, 14 at 23 ° C and 50% relative humidity
The measurement was performed after leaving it for one day. (3) Flexural rigidity: According to JIS-K7106 A 3 mm-thick sheet hot-press molded at 180 ° C. was punched out to obtain a test sample, which was 14 at 23 ° C. and 50% relative humidity.
The measurement was performed after leaving it for one day. (4) Hardness (Shore D hardness): According to JIS-K7215 A 3 mm-thick sheet hot-press molded at 180 ° C. was punched out to obtain a test piece, which was 14 at 23 ° C. and 50% relative humidity.
After standing for a day, these were piled up and measured. (5) Impact resilience: JIS-K6301 compliant Hot press molded at 180 ° C. 12.7 mm, diameter 29.
A 0 mm right cylinder-shaped test piece was used, and the measurement was performed after standing for 14 days at 23 ° C. and 50% relative humidity. (6) Impact energy: resin temperature 240 ° C, mold temperature 2
2mm thickness injection molded at 0 ° C, 120x120mm
Square plate was prepared, and allowed to stand at 23 ° C. and 50% relative humidity for 14 days, and then measured. The measurement was performed using a high-speed impact tester (manufactured by Rheometrics Co., Ltd.) with a hitting core having a hemispherical tip (diameter of 5/8 inch), and the central portion of the test piece adjusted for 12 hours in an atmosphere of -20 ° C was 12 m / sec. It was punched at the speed of and the impact energy required for breaking was measured.

Examples ~, Comparative Examples ~ Compositions shown in Table 2 were used to make resin temperatures of 185 to 190 using a 40 mmφ single screw extruder (manufactured by Nakatani Machine Co., Ltd.).
℃, melt blend at a screw rotation speed of 40 rpm,
The physical properties of the obtained composition were evaluated. The results are shown in Table 2.

Comparative Examples 1 to 3 are ionomer resin compositions for golf ball skin materials based on the prior art. In order to increase the impact resilience, the composition is a combination of a monovalent metal-neutralized ionomer and a divalent metal-neutralized ionomer based on an ethylene-methacrylic acid copolymer having a high methacrylic acid content. In these compositions, as the impact resilience increases, the rigidity increases, while a clear decrease in impact resistance is observed. It is understood that, in the conventional technique, when the impact resilience is increased, the impact resistance is additionally reduced, which is not preferable as the surface material of the golf ball. The comparative example is a composition conventionally used as a golf ball skin material (JP-A-6-79017).

Examples 1 to 3 show remarkably good impact resistance while having impact resilience almost equal to that of the comparative example having the highest impact resilience among compositions based on the prior art. These compositions include ionomer a as a monovalent metal-neutralized ionomer, which has extremely high impact resilience and high rigidity.
However, ionomers d, e, and f are used as the ionomers for neutralizing the divalent metal ion. Compared with the comparative example, the composition of the monovalent metal ion neutralized ionomer and the divalent metal ion neutralized ionomer based on the present invention has high impact resilience,
It can be seen that it shows a significantly improved impact resistance.

A similar tendency was observed when comparing Examples and Comparative Examples, and further when comparing Examples and Comparative Examples, and the composition according to the present invention had a high impact resilience and significantly improved resistance. It can be seen that it shows impact resistance.

In the comparative example, an ionomer having a slightly low neutralization degree is used as the ionomer for neutralizing the divalent metal ion, and although the impact resilience is high, the degree of improvement in impact resistance is insufficient.

[0045]

[Table 2]

[0046]

According to the present invention, an ionomer resin composition having high impact resilience and excellent impact resistance can be provided. By using such a composition as the surface of a golf ball, it is possible to provide a ball having excellent flight distance and durability upon hitting.

Claims (5)

[Claims] 1. A resin composition comprising an ionomer resin neutralized with a divalent metal ion and an ionomer resin neutralized with a monovalent metal ion, wherein the unsaturated carboxylic acid content is 5 to 10 mol%. , Melt flow rate is 110
60 to 80 mol% of the carboxyl groups of the ethylene-unsaturated carboxylic acid copolymer are neutralized with a divalent metal ion to obtain a melt flow rate of 0.
1 to 5.0 g / 10 min at least 25% by weight or more of the ionomer resin (A), and an unsaturated carboxylic acid content of 5
-10 mol% of an ethylene-unsaturated carboxylic acid copolymer is blended with an ionomer resin (B) having a flexural rigidity of 290 MPa or more obtained by neutralizing at least 20 mol% or more of the carboxyl groups with a monovalent metal ion. A resin composition having excellent impact resistance. 2. The ionomer resin composition according to claim 1, wherein the divalent metal of the ionomer resin (A) is at least one divalent metal selected from the group consisting of zinc and magnesium. 3. The ionomer resin composition according to claim 1, wherein the monovalent metal of the ionomer resin (B) is at least one monovalent metal selected from the group consisting of alkali metals such as lithium, sodium and potassium. 4. The ionomer resins (A) and (B)
The ionomer resin composition according to claim 1, wherein the unsaturated carboxylic acid is at least one unsaturated carboxylic acid selected from the group consisting of acrylic acid and methacrylic acid. 5. An ethylene-unsaturated carboxylic acid copolymer having an unsaturated carboxylic acid content of 5 to 10 mol% and a melt flow rate of 110 to 500 g / 10 min is divalent at 60 to 80 mol% of the carboxyl groups. Neutralized with the metal ion of, the melt flow rate is 0.1 to 5.0 g / 10
Of at least 25% by weight of the ionomer resin (A), and at least 20% by mole or more of the carboxyl groups of the ethylene-unsaturated carboxylic acid copolymer having an unsaturated carboxylic acid content of 5 to 10% by mole. A golf ball skin material excellent in impact resistance obtained by mixing with an ionomer resin (B) having a flexural rigidity of 290 MPa or more neutralized with metal ions.