JP3478854B2 - Ionomer and golf ball material using the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel composite ionomer having a low hygroscopic property, an excellent combination of flexibility and impact resilience, which is particularly useful as a golf ball material.

[0002]

2. Description of the Related Art Ionomer resins, which are excellent in cut resistance, impact resistance and impact resilience, are often used as the surface material of conventional two-piece golf balls and some thread-wound golf balls. An ionomer using a plurality of metal ions as metal ions is also known. For example, it is known that the impact resilience is improved more than the sodium ionomer itself by mixing the sodium ionomer excellent in impact resilience and the zinc ionomer excellent in impact resistance and cut resistance at an appropriate ratio, A golf ball using a mixture of such ionomer resins as a skin material has been proposed (US Pat. No. 3,819,768).

Further, in Japanese Patent Laid-Open No. 2-297383, a skin material for a golf ball, which is further excellent in impact resilience, contains a lithium ion ionomer, which is superior in impact resilience as compared with sodium ionomer, as a main component, and is divalent. Alternatively, a composition containing an ionomer of a trivalent metal ion has been proposed.

Further, Japanese Patent Laid-Open No. 3-207382 discloses a golf ball skin material having a high impact resilience and a low temperature durability, which has a flexural rigidity of 3000 kg / based on an ethylene-acrylic acid copolymer. cm ² (294M
Pa) or higher alkali metal ion neutralized ionomer,
A mixture of divalent metal-neutralized ionomers having a flexural rigidity of 1500 kg / cm ² (147 MPa) or more has been proposed. It is suitable when the flexural rigidity of the alkali metal ion-neutralized ionomer is less than 3000 kg / cm ² because the impact resilience is insufficient. It is said that there is no.

Further, in Japanese Patent Application Laid-Open No. 4-96771, there is disclosed an ethylene-unsaturated carboxylic acid copolymer having a high unsaturated carboxylic acid content of 16 to 30% by weight with a monovalent or divalent metal ion. A golf ball excellent in impact resilience has been proposed in which 20% by weight or more of a hydrated ionomer resin is mixed in a surface material.

[0006]

Generally, in an ionomer resin, the rigidity and the impact resilience are in a parallel relationship, and if the impact resilience as a golf ball is to be increased, the rigidity tends to be increased. There is. On the other hand, on the other hand, the feel of impact of the golf ball is closely related to the flexibility of the skin material. The more flexible the skin material, the better the feel of impact and the better the controllability of the ball.

The means found in the above-mentioned prior art is recognized as an effective method for improving the impact resilience, but at the same time, the rigidity of the skin material increases, so that a golf ball using such a skin material is Although it satisfies the user's demand to increase the distance, it also has the drawback that the feel on hitting becomes poor and the controllability of the ball is likely to deteriorate.

The ionomer used for golf balls and the like has a problem that the ionomer easily absorbs moisture in addition to the problem of the balance between flexibility and impact resilience.

The ionomer of an ethylene / (meth) acrylic acid copolymer has a hydrophilic ethylene group bonded to a hydrophobic ethylene chain as a side chain, and part or all of the carboxyl group is formed by a metal ion. It has a harmonized structure. Therefore, among plastics, it generally has a hygroscopicity intermediate between that of nylon and polyethylene, but among ionomers, alkali metal-neutralized ionomers have a hygroscopic property that is similar to that of alkaline earth metals such as magnesium and zinc. It is much larger than metal neutralized ionomers. Further, the higher the acid content or the higher the degree of neutralization, the higher the hygroscopicity of the ionomer.

Therefore, when the pellet of the alkali metal neutralized ionomer having a high acid content and a high degree of neutralization is left in a high temperature and high humidity atmosphere, it immediately absorbs moisture. When the hygroscopic ionomer resin is processed at a high temperature, water is desorbed from the resin and vaporized, so that bubbles are formed in the molten resin. Such air bubbles cause pinholes and cracks in the molded product, so that a product of satisfactory quality cannot be obtained.

Further, the ionomer resin that has once absorbed moisture cannot be used unless it is re-dried, but this drying needs to be carried out at a melting temperature of pellets (35 to 60 ° C.) or lower, and 2 to 2 using dehumidified air. Requires drying for 3 days.

Among the alkali metal neutralized ionomers,
It is known that the potassium ionomer has a remarkably high hygroscopicity (JP-A-60-240704 and JP-A-3-106954), and this potassium ionomer is still put to practical use as a skin material for golf balls. It is presumed that it is due to the extremely high hygroscopicity.

The present inventor uses an ion source of potassium and a divalent metal (M) such as zinc and magnesium, and an ionomer having an atomic ratio of K / M = 1/5 to 8/1 is: It was found that the hygroscopicity is remarkably improved as compared with the potassium ionomer, and the flexibility is remarkably improved while maintaining excellent impact resilience.

That is, an object of the present invention is to use potassium and a divalent metal (M) such as zinc or magnesium as an ion source,
(EN) It is an object to provide an ionomer and a golf ball material using the same, which have remarkably improved hygroscopicity and, while retaining excellent impact resilience, remarkably improved flexibility.

[0015]

According to the present invention, potassium and a divalent metal (M) are used as ion sources, and their atomic ratio is in the range of K / M = 1/5 to 8/1. , The total acid unit content is 3 to 14 mol%, and the degree of neutralization is 20 to
An ionomer of an ethylene / unsaturated carboxylic acid copolymer having a content of 90%, which is characterized by having an infrared absorption peak in the vicinity of 1615 cm ^-1 is provided. According to the present invention, a binary copolymer of ethylene and an unsaturated carboxylic acid, or a potassium neutralized product of a terpolymer of ethylene / (meth) acrylic acid ester and an unsaturated carboxylic acid, A binary copolymer of an ionomer (A) having a bending rigidity of 280 MPa or less and ethylene and an unsaturated carboxylic acid, or a zinc ternary copolymer of ethylene / (meth) acrylic acid ester and an unsaturated carboxylic acid, and It is composed of a blend of a divalent metal (M) neutralized product ionomer (B) selected from the group consisting of magnesium, and the atomic ratio of potassium to the divalent metal after the blending is K / M = 1 / 5 to 8/1, the total acid unit content is 3 to 14 mol% and the degree of neutralization is 20.
An ionomer is provided, which is characterized by having an infrared absorption peak in the vicinity of 1615 cm ^{−1 in} an amount of ˜90%.

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

[0017]

The ionomer of the present invention uses potassium and a divalent metal (M), especially zinc, magnesium, etc. as ion sources, and has an atomic ratio of K / M = 1/5 to 8/1, preferably 1 / 2 to 5/1, more preferably 1/1 to 5/1
It is a remarkable feature that it is in the range of. In this ionomer, the one consisting of a specific ratio of potassium ionomer and zinc ionomer is considered to be a novel substance different from a simple mixture.

Please refer to FIG. 1 of the accompanying drawings. The potassium-neutralized ionomer shows an infrared absorption peak at a wave number of 1545 cm ⁻¹ attributable to the asymmetric stretching vibration of the carboxylate group, while the zinc-neutralized ionomer shows a wave number of 1585c.
Although the infrared absorption peak of m ^-1 is shown, the potassium-zinc ionomer of the specific composition ratio used in the present invention has a new infrared absorption spectrum near the wave number of 1615 cm ^-1 which is completely different from these absorption peaks. It seems that a double salt of potassium salt and zinc salt is formed.

In the present invention, the properties of the ionic groups of the ionic aggregates change with the formation of the double salt, so that the hygroscopicity also changes, and the remarkably high hygroscopicity of the potassium ionomer is improved.

Please refer to FIG. 2 of the accompanying drawings. In this figure, the relationship between the mixing ratio and the amount of moisture absorption when the potassium ionomer is mixed with the zinc ionomer or the magnesium ionomer at various mixing ratios is plotted.
From these plots it becomes clear that the ionomers of the present invention show a much lower moisture uptake than the arithmetic mean calculated from the amount ratio of potassium ionomer to zinc ionomer or magnesium ionomer.

In the present invention, it is also extremely important to incorporate the potassium ionomer into the double salt ionomer.
FIG. 3 of the accompanying drawings is a plot of the relationship between flexural modulus and impact resilience for various alkali metal ion neutralized ionomers. According to this graph, in the sodium ionomer and the lithium ionomer, the bending rigidity and the impact resilience have a gradual proportional relationship on the high bending rigidity side, whereas the potassium ionomer has the low bending rigidity side. It is understood that there is a steep proportional relationship between the bending rigidity and the impact resilience, and it is possible to maintain the bending stiffness at a low value while maintaining the impact resilience at a high level, which can improve the feel at impact and the controllability of the ball. It

In the present invention, the atomic ratio of potassium (K) to divalent metal (M) such as zinc and magnesium is K / M = 1/5 to 8/1, especially 1/2 to 5/1. Especially, it is also important that the ratio is in the range of 1/1 to 5/1. If the atomic ratio of potassium is higher than the above range, the hygroscopicity becomes large, which is not preferable. On the other hand, when the atomic ratio of potassium is less than the above range, the impact resilience is insufficient, which is not preferable.

The total acid unit content is 3 to 14 mol%, particularly 4 to 7.5 mol%, and the degree of neutralization is 20.
To 90%, especially 30 to 80%, and when the acid unit content as a whole exceeds the above range or the degree of neutralization exceeds the above range, the hygroscopicity and moldability may be reduced. On the other hand, if the acid unit content as a whole is less than the above range or the degree of neutralization is less than the above range, the scratch resistance and high impact resilience inherent in the ionomer are lost, which is not preferable.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION The ethylene / unsaturated carboxylic acid copolymer used in the present invention includes 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,
Examples thereof include 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, and acrylic acid and methacrylic acid are preferable.

This copolymer may contain a (meth) acrylic acid ester as a copolymerization component. As the copolymerization component, for example, methyl (meth) acrylate,
Examples thereof include acrylic acid esters such as ethyl (meth) acrylate, isobutyl (meth) acrylate, and t-butyl (meth) acrylate, and methacrylic acid esters. Other monomers such as styrene or vinyl acetate may be copolymerized with this copolymer.

In such a copolymer, ethylene is generally 82 to 97 mol%, particularly 90 to 97%, and acid components such as (meth) acrylic acid are 3 to 14 mol%, especially 3 to 10%.
Mol%, 0 to 10 mol% of other unsaturated monomer components,
Those copolymerized at a ratio of 0 to 8 mol% are particularly preferable. 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 converting the ethylene-unsaturated carboxylic acid copolymer into 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.

As the divalent metal ion, beryllium,
Although ions of alkaline earth metals such as magnesium, calcium, strontium, and barium, and ions of metals such as zinc and copper can be used, zinc or magnesium ions are preferable.

In the present invention, it is preferable to use an ionomer having a neutralization degree of 10 to 90 mol%, particularly 20 to 80 mol%, and 190 ° C.
Melt flow rate at 2160g load is 0.01
~ 500 g / 10 minutes, especially 0.1-100 g / 10
Min, and most preferably about 0.5 to 15 g / 10 min.

When the melt flow rate is smaller than the above range, the fluidity is low, the moldability is deteriorated, and the impact resistance is deteriorated. Further, if it exceeds the above range, there are drawbacks such as deterioration of impact resilience and impact resistance.

The ionomer of the present invention contains potassium and a divalent metal (M) such as zinc or magnesium in the above-mentioned atomic ratio, and its production method is not particularly limited. Generally, a potassium-neutralized ionomer of an ethylene / unsaturated carboxylic acid copolymer and a divalent metal-neutralized ionomer of an ethylene / unsaturated carboxylic acid copolymer are melt-mixed at a predetermined ratio that gives the atomic ratio. Can be obtained by

The conditions for melt-mixing are such that, in a compound capable of forming a double salt, the infrared absorption peak attributed to the asymmetric stretching vibration of the carboxylate group of the resulting composition is a potassium-neutralized ionomer (near 1545 cm ^-1). ) Or a divalent metal-neutralized ionomer (in the case of zinc, in the vicinity of 1585 cm ⁻¹ ) different from that in the vicinity of 1615 cm ⁻¹ ,
Any condition is acceptable. The simplest method is, for example, a method in which a potassium-neutralized ionomer and a divalent metal-neutralized ionomer are melt-kneaded at a temperature of 100 to 250 ° C. in a single-screw or twin-screw extruder.

Another method for obtaining the ionomer composition of the present invention is to preliminarily mix a predetermined amount of the above-mentioned potassium compound serving as an ion source and a divalent metal compound, and then react with the ethylene / unsaturated carboxylic acid copolymer. Can also be obtained by At this time, the raw materials for the ionization reaction are preferably melt-kneaded at a temperature of 180 to 280 ° C. with a single-screw or twin-screw extruder. Further, it is preferable to use a vent type extruder to remove by-produced water, carbon dioxide gas and the like. The difference in this method is not essential. In the present invention,
This is because ion exchange may occur between the copolymer and the two types of metal ions in the kneading process, and double salt may be produced by homogenization. Therefore, the blending method will be described below exclusively, but is not limited to this example.

In a preferred embodiment of the present invention, the potassium ion-neutralized ionomer resin (A) contains an ethylene-unsaturated carboxylic acid copolymer having an unsaturated carboxylic acid content of 10 to 25% by weight, preferably 13 to 20% by weight. The carboxyl group of the polymer is neutralized with potassium ions at 20 to 80 mol%, preferably 25 to 70 mol%, and the flexural modulus is 280 MPa.
Hereinafter, it is preferable to use an ionomer resin having a pressure of preferably 200 to 280 MPa.

If the unsaturated carboxylic acid content is less than 10% by weight, a composition having a high impact resilience cannot be obtained, and if the unsaturated carboxylic acid content is more than 25% by weight, the hardness and rigidity are high. It is not preferable because the hygroscopicity becomes extremely high.

The degree of neutralization with potassium ions is 20 mol%
If it is less than 80 mol%, the impact resilience will be insufficient, and if it exceeds 80 mol%, the hygroscopicity will be remarkably increased and the fluidity will be extremely lowered to deteriorate the moldability, which is not preferable.

If the flexural rigidity exceeds 280 MPa, the feel at impact of the ball will deteriorate, which is not preferable.

As the potassium ionomer (A), 1
It is preferable that the melt flow rate at 90 ° C. under a load of 2160 g is 0.1 to 30 g / 10 minutes, particularly 0.5 to 15 g / 10 minutes.

In a preferred embodiment of the present invention, the divalent metal ion-neutralized ionomer resin (B) has an unsaturated carboxylic acid content of 8 to 30% by weight, preferably 13 to 25% by weight. It is preferable to use an ionomer resin in which the carboxyl group of the copolymer is neutralized with a divalent metal ion, preferably zinc ion or magnesium ion, in an amount of 20 mol% or more, preferably 25 mol% or more.

When the unsaturated carboxylic acid content is less than 8% by weight, the impact resilience is insufficient, and when the unsaturated carboxylic acid content is more than 30% by weight, the hardness and rigidity are high and the durability against impact is lowered. It is not preferable to do.

When the degree of neutralization with a divalent metal ion is less than 20 mol%, the impact resilience is low and the durability is insufficient, which is not preferable.

As the ionomer (B) neutralized with a divalent metal ion, the melt flow rate at 190 ° C. under a load of 2160 g is 0.1 to 30 g / 10 minutes, and particularly, 0.1.
It is preferably 5 to 15 g / 10 minutes.

The mixing ratio of the potassium ionomer (A) and the divalent metal ion-neutralized ionomer (B) gives the above-mentioned atomic ratio, but generally 20 to 80% by weight of the potassium ionomer (A), Particularly preferably 25 to 75% by weight, and the divalent metal ion-neutralized ionomer (B) is 80 to 20% by weight, particularly preferably 75 to 2%.
It is desirable to use 5% by weight.

The ionomer 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, and weather resistance stabilizers. Typical additives are, for example, pigments such as titanium oxide, zinc oxide, barium sulfate and zinc sulfate, various dyes and pigments.

The skin of the ionomer of the present invention can be used for coating any of known solid golf ball cores and wound golf ball cores. The solid core is a rubber composition mainly composed of rubber which is vulcanized and integrally molded, and the thread wound core is a threaded rubber wound around a core body.

The method of coating the core with the skin material is not particularly limited, and a usual 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 injection molding of 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 if necessary, and the obtained ball is finished with paint as necessary.

[0048]

The present invention will be described in more detail with reference to the following examples. The ionomer resins used for preparing the composition of the present invention are shown in Table 1.

[0049]

[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 2180 g (2) Flexural rigidity: JIS-K7106 compliant 180 ° C. hot-press molded sheet having a thickness of 3 mm was punched out to obtain a test piece, This was tested. (3) Hardness (Shore D hardness): A sheet with a thickness of 3 mm, which was hot press molded at 180 ° C. according to JIS-K7215, was punched out to obtain a test piece, which was piled up and tested. (4) Rebound resilience Hot-press molded at 180 ° C. according to JIS-K6301 thickness 12.7 mm, diameter 2
The test was performed using a 9.0 mm right circular cylinder type test piece. (5) Hygroscopicity: A 1 mm thick sheet hot-press molded at 180 ° C. was punched out into a 20 mm width × 100 mm length to give a test piece, which was immersed in 20 ° C. water for 24 hours, and then the water content (surface adhering water) Was measured to determine the hygroscopicity.

Examples ~, Comparative Examples The compositions having the 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 Machinery 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.

In the case of the ionomer resins alone of Comparative Examples to Comparative Examples, the physical properties were evaluated as they are, and the results are shown in Table 2.

Comparing potassium and sodium belonging to the same alkali metal as the ion species of the ionomer, the potassium ionomer shown in the comparative example has the same impact resilience and hardness as compared with the sodium ionomer shown in the comparative example. And the rigidity is low. Therefore, when a potassium ionomer is used as the surface of a golf ball, it is expected that the impact resilience of the hole, that is, the shot feeling is improved while maintaining the flight distance.

However, the potassium ionomer of the comparative example has a remarkably higher hygroscopicity than the ionomers of other ionic species (comparative example), and the foaming phenomenon is caused by the water content in the resin when molding the ball skin. Therefore, in order to prevent moisture absorption of the resin, it is necessary to consider handling more than ionomers of other ionic species.

In the case of the composition of the example in which the potassium ionomer was blended with the ionomer neutralized with zinc ion which is a divalent metal ion at a ratio of 50/50% by weight, the hygroscopicity was remarkably reduced as compared with the potassium ionomer alone. Has been done. The hygroscopicity of the composition according to the invention is shown in FIG.

Further, when the physical properties of the composition of the example are compared with the composition of the comparative example which is generally used as a ball skin material, the impact resilience is exactly the same, but the hardness and rigidity are lowered, and It is considered that the use of the composition for the skin material improves the shot feeling while maintaining the flight distance of the ball.

In the case of the compositions of the examples and the compositions in which the mixing ratio of the potassium ionomer and the zinc ionomer was changed, the hygroscopicity was slightly increased as the mixing ratio of the potassium ionomer increased, but from the mixing ratio of both ionomers. The actual hygroscopicity is greatly reduced compared to the expected hygroscopic amount. Furthermore, the compositions of Examples and 1 have good impact resilience, but their rigidity is lower than that of Comparative Examples.

Examples-and Comparative Examples The compositions of Examples-shown in Table 3 were melt-blended under the same conditions as those of Examples-, and their physical properties were evaluated. In the case of the resin alone of the comparative example, the physical properties were evaluated as it was. The results are shown in Table 3.

The impact resilience of the compositions of Examples 1 to 3 is almost the same as the impact resilience of the Comparative Examples, but the flexural rigidity is lowered. In addition, the hygroscopicity is also lower than the value estimated from the hygroscopicity of the constituent ionomer alone and its blending ratio.

[0060]

[Table 2]

[0061]

[Table 3]

[0062]

The ionomer of the present invention has an absorption spectrum different from the infrared absorption peak attributed to the asymmetric stretching vibration of the carboxylate group of the potassium-neutralized ionomer and the zinc-neutralized ionomer, as shown in Examples and drawings. Have It is believed that the ionomer of the present invention forms a double salt from this molecular structure and the fact that the physical properties are improved as described above.

According to the present invention, it is hard to be scratched, has excellent durability against impact, has good impact resilience, and
It is soft and has improved feel on impact, and also has reduced hygroscopicity, and is useful as a golf ball skin material.

[Brief description of drawings]

FIG. 1 is a diagram showing a mixing ratio of potassium ion and zinc ion of ethylene ionomer and a change in asymmetric stretching vibration absorption of a carboxylate group in an infrared spectrum.

FIG. 2 is a graph plotting the relationship between the amount of moisture absorption and the compounding ratio when the potassium ionomer is compounded at various compounding ratios with zinc ionomer or magnesium ionomer.

FIG. 3 is a graph plotting the relationship between flexural rigidity and impact resilience for various alkali metal ion neutralized ionomers.

Claims (8)

(57) [Claims] 1. An ion source of potassium and a divalent metal (M), the atomic ratio of which is in the range of K / M = 1/5 to 8/1, and the total acid unit content is 3. An ionomer of an ethylene / unsaturated carboxylic acid copolymer having a degree of neutralization of 20 to 90% and a concentration of 1615c
An ionomer having an infrared absorption peak in the vicinity of m ⁻¹ . 2. The divalent metal (M) is a divalent metal selected from the group consisting of zinc and magnesium.
The described ionomer. 3. An ethylene / unsaturated carboxylic acid copolymer is a binary copolymer of ethylene and an unsaturated carboxylic acid, or a terpolymer of ethylene / (meth) acrylic acid ester and an unsaturated carboxylic acid. The ionomer according to claim 1 or 2, which is 4. A binary copolymer of ethylene and an unsaturated carboxylic acid, or a terpolymer of ethylene / (meth) acrylic acid ester and an unsaturated carboxylic acid is selected from the group consisting of potassium, zinc and magnesium. The ionomer according to any one of claims 1 to 3, which is obtained by neutralizing a combination with a selected divalent metal (M) as an ion source. 5. A potassium-neutralized product of a binary copolymer of ethylene and an unsaturated carboxylic acid, or a terpolymer of an ethylene / (meth) acrylic acid ester and an unsaturated carboxylic acid, having a pressure of 280 MPa or less. An ionomer (A) having bending rigidity and a binary copolymer of ethylene and an unsaturated carboxylic acid, or a ternary copolymer of ethylene / (meth) acrylic acid ester and an unsaturated carboxylic acid, zinc and magnesium. It consists of a blend of a neutralized product of a divalent metal (M) selected from the group Ionomer (B), and the atomic ratio of potassium to the divalent metal after the blending is K / M.
= 1/5 to 8/1, the total acid unit content is 3 to 14 mol%, the degree of neutralization is 20 to 90%, and infrared absorption is in the vicinity of 1615 cm ^-1. An ionomer having a peak. 6. A flexural modulus obtained by neutralizing 20 to 80 mol% of the carboxyl groups of an ethylene / unsaturated carboxylic acid copolymer having an unsaturated carboxylic acid content of 10 to 25% by weight with potassium ions. Of 280 MPa or less of the ionomer resin (A) is 20 to 80% by weight, and 20 mol% or more of the carboxyl groups of the ethylene / unsaturated carboxylic acid copolymer having an unsaturated carboxylic acid content of 8 to 30% by weight are divalent. Ionomer resin (B) 80 to 20 neutralized with metal ions
The ionomer according to claim 5, wherein the ionomer is blended in a weight percentage. 7. A golf ball material comprising the ionomer according to any one of the preceding claims. 8. The golf ball material according to claim 7, wherein the ionomer has a bending rigidity of 280 MPa or less and a impact resilience of 55% or more.