JP3519131B2 - Resin composition excellent in impact resistance and skin material of golf ball - Google Patents

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. In particular, 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 inventors of the present invention have determined that a specific ionomer obtained by neutralizing an ethylene-methacrylic acid copolymer having a relatively high melt flow rate with a divalent metal ion in a predetermined ratio and an ethylene- methacrylic acid copolymer are monovalent. With a specific ionomer of high impact resilience and high rigidity neutralized with the metal ion of
It has been found that by blending in a predetermined ratio, impact resistance is remarkably improved while having high impact resilience.

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, ethylene-methacrylic acid copolymers neutralized with divalent metal ions.
Ethylene-methacrylate neutralized with the body and monovalent metal ions
In a resin composition containing an acid copolymer , methacrylic acid
Acid content 5-10 mol%, melt flow rate 1
72 to 80 mol% of the carboxyl groups of an ethylene- methacrylic acid copolymer of 10 to 500 g / 10 min are neutralized with a divalent metal ion, and the melt flow rate thereof is 0.
At least 25% by weight or more of the ionomer resin (A) at 1 to 5.0 g / 10 minutes and a methacrylic acid content of 5 to 1
Impact resilience prepared by blending 0 mol% of an ethylene- methacrylic acid copolymer with at least 20 mol% of carboxyl groups neutralized with a monovalent metal ion and an ionomer resin (B) having a flexural rigidity of 290 MPa or more. And a resin composition having excellent impact resistance is provided.

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, a carboxyl group of an ethylene- methacrylic acid copolymer having a methacrylic acid content of 5 to 10 mol% and a melt flow rate of 110 to 500 g / 10 min. Of 7
2 to 80 mol% of divalent metal ions, especially zinc ions,
An ionomer resin (A) neutralized with magnesium ions and having a melt flow rate of 0.1 to 5.0 g / 10 min, and a highly rigid specific monovalent metal ion neutralized ionomer, that is, a methacrylic acid content. Of 5-10 mol%
At least 20 mol% or more of the carboxyl groups of the ethylene-methacrylic acid copolymer are neutralized with a monovalent metal ion, particularly an alkali metal ion, and an ionomer resin (B) having a bending rigidity of 290 MPa or more is selected. By blending and combining at least 25% by weight or more of the ionomer resin (A), a resin composition for a golf ball skin material having high impact resilience and significantly improved impact resistance can be obtained.

It is important to use a golf ball skin material composed of an ionomer composition with a high impact resilience in order to increase the flight distance of a ball required by a golfer, while a high impact 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 above specific ethylene- meta
Select divalent metal ion-neutralized ionomer of acrylic acid copolymer (A), which certain high impact resilience at and high rigidity ethylene - it is combined with the monovalent metal ion-neutralized ionomer of methacrylic acid copolymer It has succeeded in remarkably 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]

Ethylene used in the present invention a preferred embodiment of the invention] - unsaturated carboxylic acid polymer, binary copolymer of ethylene and methacrylic acid, or ethylene, methacrylic acid and main
A terpolymer of tacrylic acid ester is used.

[0018]

The copolymer may contain a methacrylic acid ester as a copolymerization component, and examples of the copolymerization component include methyl methacrylate and methacrylic acid.
Ethyl, n-butyl methacrylate, isobutymethacrylate
Examples thereof include methacrylic acid esters such as chill .

The copolymerization ratio of such methacrylic 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 already known, the ionomerization method is carried out by using the ethylene- methacrylic acid copolymer
Metal hydroxides, oxides, carbonates, bicarbonates, acetates,
There is a method of partially or completely neutralizing the alkoxide or the like in a molten state or in a state of being dissolved or suspended in a medium such as water.

In a preferred embodiment of the invention, ethylene- meta
As the divalent metal ion neutralized ionomer (A) of the acrylic acid copolymer, the content of methacrylic acid is 5 to 10 mol%,
Preferably 5.4-8.5 mol%, melt flow rate 110-500 g / 10 minutes, preferably 150-35
72 to 80 mol% of the carboxyl groups of the ethylene- methacrylic acid copolymer at 0 g / 10 min are converted to divalent metal ions,
It is preferably neutralized with ions of at least one divalent metal selected from the group consisting of zinc and magnesium, particularly preferably zinc ions, and has a melt flow rate of 0.1 to 5.0 g / 10 minutes, preferably Is 0.4 to 4.
It is preferable to use an ionomer of 5 g / 10 min.

When a copolymer having a methacrylic acid content less than the above range is used, a composition having a high impact resilience cannot be obtained, and when a copolymer having a methacrylic acid content of more than 10 mol% is used, hygroscopicity is obtained. Is large and the impact resistance decreases, which is not preferable.

190 of ethylene- methacrylic acid copolymer
Melt flow rate at 2 ° C, 2160 load is 110
If it is less than g / 10 minutes, the flowability of the ionomer neutralized with metal ions in the molten state becomes too low, which hinders moldability and the melt flow rate of the ethylene- methacrylic acid copolymer is 500 g / If it is longer than 10 minutes, the impact resistance is inferior, which is not preferable.

When the degree of neutralization of the ethylene- methacrylic acid copolymer with divalent metal ions is lower than 72 mol%, the degree of improvement in impact resistance of the composition is low and the degree of neutralization is 80.
When it is more than mol%, the fluidity of the ionomer in the molten state becomes too low and the moldability is impaired, which 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 invention, ethylene- meta
As the monovalent metal ion neutralized ionomer (B) of the acrylic acid copolymer , the methacrylic acid content is 5 to 10 mol%,
Preferably 5.4 to 8.5 mol% ethylene- methacrylate
At least 20 mol% of the carboxyl groups of the acid copolymer
As described above, preferably 25 to 60 mol% is neutralized with a monovalent metal ion, preferably with an ion of at least one metal selected from the group consisting of alkali metals such as lithium, sodium and potassium, and the bending rigidity is 290 MPa or more, preferably. Is preferably an ionomer having a pressure of 300 MPa or more.

When a copolymer having a methacrylic acid content of less than 5 mol% is used, a composition having high impact resilience cannot be obtained, and when a copolymer having a methacrylic acid content of more than 10 mol% is used, moisture absorption is reduced. It is not preferable because it has high properties and the 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.

The divalent metal ion-neutralized ionomer (A) of the ethylene- methacrylic acid copolymer of the present invention and ethylene-
The composition of the methacrylic acid copolymer with the monovalent metal ion-neutralized ionomer (B) preferably contains at least 25% by weight of the ionomer (A) when the total weight is 100% by weight.

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 180 ° C. hot stamped 2 mm thick sheet was punched out to obtain a test piece, 14 at 23 ° C and 50% relative humidity
The measurement was performed after leaving it for one day. (3) Bending rigidity: A 3 mm-thick sheet hot-press molded at 180 ° C. according to JIS-K7106 was punched out to obtain a test piece, 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): A 3 mm-thick sheet hot-press molded at 180 ° C. according to JIS-K7215 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) Rebound resilience: JIS-K6301 conforming to hot press molding 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.

Reference Example 1, Examples 2 to 5, Comparative Examples 1 to 4 The compositions having the compositions shown in Table 2 were used, and the resin temperature was 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 2 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 according to the present invention may have a significantly improved impact resistance while having a high impact resilience. I understand.

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 (4)

(57) [Claims] 1. Ethylene neutralized with a divalent metal ion
In a resin composition comprising a methacrylic acid copolymer and an ethylene-methacrylic acid copolymer neutralized with a monovalent metal ion, the methacrylic acid content is 5 to 10 mol% and the melt flow rate is 110 to 500 g. / 10 to 72 minutes of the carboxyl group of the ethylene- methacrylic acid copolymer
0 mol% becomes neutralized with divalent metal ions, and a melt flow rate of 0.1 to 5.0 g / 10 min of the ionomer resin (A) at least 25% by weight or more, Metaku
Ethylene- methacrylic acid having a phosphoric acid content of 5 to 10 mol%
Flexural rigidity 290MP in which at least 20 mol% or more of the carboxyl groups of the acid copolymer are neutralized with monovalent metal ions
A resin composition having excellent impact resistance, which is obtained by blending an ionomer resin (B) having a or more. 2. The 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 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. A methacrylic acid content of 5 to 10 mol%,
Melt flow rate of 110-500 g / 10 min 72- of the carboxyl groups of ethylene- methacrylic acid copolymer
80 mol% becomes neutralized with divalent metal ions, and a melt flow rate of 0.1 to 5.0 g / 10 min of the ionomer resin (A) at least 25% by weight or more, meta
Ethylene- methacrylate containing 5-10 mol% acrylic acid
At least 20 mol% of the carboxyl groups of the acid copolymer
Bending rigidity 290M obtained by neutralizing the above with monovalent metal ions
A golf ball skin material excellent in impact resistance obtained by mixing with an ionomer resin (B) having Pa or more.