JP3597965B2 - Golf ball material and new ionomer - Google Patents

Description

【００４２】
【表２】

【００４３】
本発明の効果を明確に示すために、図１を用いて説明する。図１は実施例１、２、比較例１〜５で得られたアイオノマーの反発弾性率と硬度の関係を示している。この図からわかる通り、マグネシウム／ナトリウム共イオン化アイオノマー（実施例１及び２）はベースレジン及びトータルの中和度を同じくするマグネシウムアイオノマー（比較例１）やナトリウムアイオノマー（比較例２）よりも反発弾性率が高くなっている。これはマグネシウム／ナトリウムの組み合わせに特異的な現象であり、マグネシウム／亜鉛やナトリウム／亜鉛の組み合わせによる共イオン化アイオノマー（比較例４、５）では、原料ポリマーの物性を大きく上回るようなことはない。
【００４４】
【発明の効果】
本発明によれば、低硬度で反発弾性の大きいゴルフボール材料を容易に提供することができる。かかる材料を使用したゴルフボールは、スピンがよくかかり、コントロール性が優れており、また打球感にも優れている。
【図面の簡単な説明】
【図１】実施例及び比較例で得られたアイオノマー組成物の反発弾性と硬度の関係を示すグラフである。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a golf ball material having low hardness and high rebound resilience. More specifically, the present invention relates to a golf ball material which is excellent in controllability and can provide a golf ball to which spin is easily applied. Furthermore, the present invention relates to novel ionomers.
[0002]
[Prior art]
Ethylene copolymer ionomers are widely used as golf ball cover materials because of their good durability. Conventionally, hard ionomers have been used exclusively because of the emphasis on flight distance, but in recent years, a cover that is a soft ionomer component for players who value controllability, easy spinning, shot feeling, etc. Lumber is also being used.
[0003]
For example, many proposals have been made to use a blend of a soft ionomer and a hard ionomer as a golf ball cover material. The inventions proposed in Japanese Unexamined Patent Publication Nos. Hei 5-3991, WO95 / 00212, WO95 / 11273 are representative examples.
[0004]
In these proposals, the most common mode is to use a soft ionomer of sodium or zinc in combination with a hard ionomer such as lithium, sodium or zinc. In these proposals, the reason why the hard ionomer and the soft ionomer are used in combination is that a blend of soft ionomers could not obtain a ball having excellent controllability, rebound resilience and durability.
[0005]
However, in a combination of a soft ionomer and a soft ionomer, it is not easy to soften without sacrificing the rebound resilience, that is, to improve the controllability of the ball, and the above-mentioned proposal does not provide a sufficiently satisfactory performance. I couldn't.
[0006]
Japanese Patent Application Laid-Open No. 5-277208 discloses a golf ball having excellent playability, durability, and rebound resilience by using a cover material composed of two or more soft ionomers whose metal ion species is sodium and zinc. Although it can be provided, according to the study of the present inventors, although excellent playability is obtained, it is inferior to the above-mentioned combination of the conventional hard ionomer and soft ionomer in rebound resilience.
[0007]
[Problems to be solved by the invention]
As an improvement over these conventional techniques, the present inventors have previously developed a golf ball material comprising a combination of a hard magnesium ionomer and a soft alkali metal ionomer or a blend of a specific ethylene copolymer with magnesium ions and alkali metal ions. A golf ball material made of co-ionized material was found and proposed in Japanese Patent Application No. 8-138903.
[0008]
As a result of further studies by the present inventors, a golf ball having satisfactory performance without using a hard ionomer and without using two or more ethylene copolymers in coionization. As a result, the present invention has been achieved.
[0009]
Therefore, an object of the present invention is to provide a golf ball material having excellent flexibility, rebound resilience, and durability.
Another object of the present invention is to provide a novel ionomer useful as a golf ball material.
[0010]
[Means for Solving the Problems]
The present invention relates to an ethylene / (meth) acrylic acid / (meth) acrylate copolymer having a (meth) acrylic acid content of 7 to 15% by weight and a (meth) acrylic acid ester content of 7 to 15% by weight. 30 to 70 parts by weight of magnesium ionomer (A) having a degree of neutralization of 40 to 80%, and 7 to 15% by weight of (meth) acrylic acid and 7 to 15% by weight of (meth) acrylate ester A golf ball material comprising a lithium or sodium ionomer (B) having a degree of neutralization of 30 to 80% and 30 to 70 parts by weight of an ethylene / (meth) acrylic acid / (meth) acrylic acid ester copolymer (hereinafter simply referred to as a "ball"). (Referred to as first golf ball material).
[0011]
The present invention also provides an ethylene / (meth) acrylic acid / (meth) acrylic acid ester copolymer having a (meth) acrylic acid content of 7 to 15% by weight and a (meth) acrylic acid ester content of 7 to 15% by weight. The present invention relates to a golf ball material (hereinafter, simply referred to as a second golf ball material) comprising a co-ionized ionomer having a degree of neutralization of 20 to 40% with magnesium ions and a degree of neutralization of 15 to 50% with lithium ions or sodium ions. .
[0012]
The present invention further provides an ethylene / (meth) acrylic acid / (meth) acrylic acid ester copolymer having a (meth) acrylic acid content of 7 to 15% by weight and a (meth) acrylic acid ester content of 7 to 15% by weight. The present invention relates to a coionized ionomer having a degree of neutralization of 20 to 50% with magnesium ions and a degree of neutralization of 15 to 40% with lithium ions or sodium ions (hereinafter referred to as a new ionomer).
[0013]
DETAILED DESCRIPTION OF THE INVENTION
[Action]
1. It is a remarkable feature that the first golf ball material of the present invention comprises a combination of a soft ionomer of a specific composition of magnesium type and a soft ionomer of a specific composition of lithium or sodium type. Despite the combination of the soft ionomer composition, high rebound resilience of 60% or more in rebound resilience is achieved, and excellent flight distance. In addition, since the combination of soft ionomers is used, flexibility of Shore D hardness of 58 or less is achieved, and the shot feeling is excellent. This golf ball material is also excellent in durability.
2. According to the present invention, an ionomer having a specific composition co-ionized with magnesium ions and lithium ions or sodium ions is provided.
3. By using this co-ionized ionomer as a golf ball material, a high rebound resilience of 60% or more in rebound resilience is achieved, while having a soft ionomer composition, and the flight distance is excellent. In addition, since it is a soft ionomer, flexibility with a Shore D hardness of 58 or less is achieved, and the shot feeling is excellent. This golf ball material is also excellent in durability.
[0014]
[First golf ball material]
The first feature of the first golf ball material of the present invention is that a specific magnesium ionomer (A) is selected, and as a base polymer, the content of (meth) acrylic acid is 7 to 15% by weight, preferably Uses an ethylene / (meth) acrylic acid / (meth) acrylate copolymer having a content of 9 to 13% by weight and a content of (meth) acrylic acid of 7 to 15% by weight, preferably 9 to 13% by weight; A material having a degree of neutralization with magnesium ions of 40 to 70%, preferably 45 to 65% is used.
[0015]
When an alkali metal ionomer or a zinc ionomer is used instead of a magnesium ionomer, the desired effect is achieved even if an ionomer having the same degree of neutralization is used even if the base polymer having the same acid content and ester content is used. Can not.
[0016]
When the content of the (meth) acrylic acid in the base polymer is smaller than the above range, it is difficult to obtain a blend having a sufficiently high rebound resilience, and when the content exceeds the above range, the content of the blend becomes large. Since the rebound resilience does not increase so much as the hardness increases, the balance between the flexibility and the rebound resilience is poor, and the hygroscopicity also increases, so that processing troubles are likely to occur.
[0017]
Further, if the ester content is less than the above range, it is difficult to obtain a low-hardness blend because of poor flexibility. On the other hand, if the ester content is too large, the composition becomes too flexible, Will be inferior.
[0018]
The degree of neutralization by the magnesium ionomer is very important in the present invention. If the degree of neutralization is less than 40%, a synergistic improvement in the rebound resilience cannot be expected, while the degree of neutralization exceeds 80%. When a material is used, the melt fluidity is extremely deteriorated due to a high degree of neutralization, and the state of blending with the ionomer (B) may be deteriorated.
[0019]
The magnesium ionomer (A) also has a melt flow rate at 190 ° C. and a load of 2160 g of 0.01 to 20 g / 10 min, particularly 0.1 to 10 g / 10 min, and a flexural rigidity of 50 to 200 MPa, preferably 70 to 200 MPa. It is preferable to use those having a pressure of 150 MPa and a Shore D hardness of 42 to 58, preferably 45 to 56.
[0020]
Even if a zinc ionomer is used instead of such a magnesium ionomer, it is difficult to obtain a blend having high rebound resilience.
[0021]
The second feature of the first golf ball material of the present invention is that the magnesium ionomer (A) is combined with a specific lithium or sodium ionomer (B) in a specific quantitative ratio. That is, together with the magnesium ionomer (A), the base polymer has a (meth) acrylic acid content of 7 to 15% by weight, preferably 9 to 13% by weight and a (meth) acrylic acid ester content of 7 to 15% by weight, Preferably, an ethylene / (meth) acrylic acid / (meth) acrylate copolymer is used in an amount of 9 to 13% by weight, and the degree of neutralization with lithium ions or sodium ions is 30 to 70%, preferably 35 to 65%. Use
[0022]
The reason for defining the (meth) acrylic acid content and the (meth) acrylate content in the base polymer of the component (B) is the same as in the case of the ionomer (A).
[0023]
Furthermore, if the ionomer (B) has a degree of neutralization of less than 30%, it is difficult to obtain a blend having a high rebound resilience, and if the degree of neutralization exceeds 80%, the melt fluidity is poor. Therefore, it is difficult to obtain a good blend.
[0024]
The ionomer (B) also has a melt flow rate of 0.01 to 20 g / 10 minutes, particularly 0.1 to 10 minutes, a flexural rigidity of 50 to 200 MPa, particularly 70 to 150 MPa, and a Shore D hardness of 42 to 58, particularly It is preferable to use those of 45 to 56.
[0025]
The (meth) acrylate component of the base polymer of the ionomer (A) and the ionomer (B) includes methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, isooctyl acrylate, Examples thereof include methyl methacrylate, ethyl methacrylate, and isobutyl methacrylate.
[0026]
The mixing ratio of the magnesium ionomer (A) and the ionomer (B) is such that the component (B) is 30 to 70 parts by weight, preferably 35 to 70 parts by weight, preferably 40 to 65 parts by weight, based on the component (A). It is in the range of 60 parts by weight (the total of both is 100 parts by weight). The blend is preferably blended so that the Shore D hardness in the blend of both (without additives) is 58 or less, preferably 56 or less, and the rebound resilience is 60% or more.
[0027]
[New ionomer and golf ball material]
The ionomer and the golf ball material having the same properties as the first golf ball material of the present invention have a (meth) acrylic acid content of 7 to 15% by weight, preferably 9 to 13% by weight, and a (meth) acrylic acid ester. An ethylene / (meth) acrylate copolymer having a content of 7 to 15% by weight, preferably 9 to 13% by weight, a degree of neutralization with magnesium ions of 20 to 50%, preferably 25 to 45%, lithium It can be obtained by co-ionization so that the degree of neutralization with ions or sodium ions is 15 to 40%, preferably 20 to 35%.
[0028]
The reason for limiting the numerical value of the second golf ball material is the same as that of the first golf ball material, and a blend having a Shore D hardness of 58 or less, preferably 56 or less and a rebound resilience of 60% or more can be easily prepared. Obtainable.
[0029]
For such co-ionization, various compounds of magnesium and lithium or sodium, for example, oxides, hydroxides, carbonates, bicarbonates, fatty acid salts and the like can be used. Co-ionization can be carried out according to a known method for producing a normal ionomer.
[0030]
[Golf ball]
The first and second golf ball materials can be used as cover materials for two-piece or three-piece balls. In such a cover material, in the case of a dual cover, it can be used as an outer layer or inner layer cover material.
[0031]
The first and second cover materials can also be used as one-piece ball materials.
[0032]
When used as a golf ball material, additives can be arbitrarily compounded and used. Examples of such additives include antioxidants, weather stabilizers, light stabilizers, ultraviolet absorbers, lubricants, pigments, dyes, inorganic fillers, and the like.
[0033]
【Example】
Next, the present invention will be described with reference to Examples and Comparative Examples.
Physical property values in Examples and Comparative Examples were measured by the following methods.
-MFR: JIS K7210, temperature 190 ° C, load 2160g
・ Hardness (Shore D): conforms to ASTM D2240 ・ Flexural rigidity: conforms to JIS K7106 ・ Rebound resilience: conforms to JIS K6301
Example 1
Using a vented single screw extruder (screw diameter 65 mm, L / D = 33), ethylene / methacrylic acid / acrylate ester terpolymer (methacrylic acid content 10% by weight, isobutyl acrylate content 10%) %, MFR35) was co-ionized with a magnesium ion source and a sodium ion source to prepare a magnesium / sodium co-ionized ionomer. The obtained coionized ionomer resin was hot-pressed into a predetermined shape, and various physical properties were evaluated by the methods described above. Table 1 shows the degree of neutralization of the coionized ionomer resin and the measurement results of physical properties.
[0035]
Comparative Example 1
In Example 1, a magnesium ionomer (ionomer resin 1) was prepared using only a magnesium ion source as an ion source, and the physical properties were measured. Table 1 shows the neutralization degree of the ionomer resin 1 and the measurement results of the physical properties.
[0036]
Comparative Example 2
In Example 1, a sodium ionomer (ionomer resin 2) was prepared using only a sodium ion source as an ion source, and the physical properties were measured. Table 1 shows the neutralization degree of the ionomer resin 2 and the measurement results of the physical properties.
[0037]
Comparative Example 3
In Example 1, a zinc ionomer (ionomer resin 3) was prepared using a zinc ion source as an ion source, and the physical properties were measured. Table 1 shows the neutralization degree of the ionomer resin 3 and the measurement results of the physical properties.
[0038]
Example 2
The ionomer resin 1 obtained in Comparative Example 1 and the ionomer resin 2 obtained in Comparative Example 2 were mixed in a single screw extruder (screw diameter 30 mm, L / D = 28) at the compounding ratio shown in Table 2. The mixture was supplied and melt-kneaded under the conditions of a melting temperature of 200 ° C. and a screw rotation speed of 40 rpm to prepare a magnesium / sodium coionized ionomer. Table 2 shows the degree of neutralization of the coionized ionomer resin and the measurement results of physical properties.
[0039]
Comparative Example 4
In Example 2, a magnesium / zinc coionized ionomer was prepared by using the ionomer resin 3 in place of the ionomer resin 2. Table 2 shows the measurement results of physical properties.
[0040]
Comparative Example 5
In Example 2, an ionomer resin 3 was used in place of the ionomer resin 1 to prepare a sodium / zinc coionized ionomer. Table 2 shows the measurement results of physical properties.
[0041]
[Table 1]

[0042]
[Table 2]

[0043]
In order to clearly show the effect of the present invention, a description will be given with reference to FIG. FIG. 1 shows the relationship between the rebound resilience and the hardness of the ionomers obtained in Examples 1 and 2 and Comparative Examples 1 to 5. As can be seen from this figure, the magnesium / sodium coionized ionomer (Examples 1 and 2) has a higher rebound than the base resin and the magnesium ionomer (Comparative Example 1) and the sodium ionomer (Comparative Example 2) having the same degree of neutralization. The rate is higher. This is a phenomenon specific to the magnesium / sodium combination, and the co-ionized ionomers (comparative examples 4 and 5) using the magnesium / zinc and sodium / zinc combinations do not significantly exceed the physical properties of the raw material polymer.
[0044]
【The invention's effect】
According to the present invention, a golf ball material having low hardness and high rebound resilience can be easily provided. A golf ball using such a material has good spin, excellent controllability, and excellent shot feeling.
[Brief description of the drawings]
FIG. 1 is a graph showing the relationship between the rebound resilience and the hardness of the ionomer compositions obtained in Examples and Comparative Examples.

Claims (4)

Neutralization degree of ethylene / (meth) acrylic acid / (meth) acrylate copolymer having (meth) acrylic acid content of 7 to 15% by weight and (meth) acrylic acid ester content of 7 to 15% by weight Is 30 to 70 parts by weight of a magnesium ionomer (A) having a content of 40 to 80%, and ethylene ((meth) acrylic acid content of 7 to 15% by weight and (meth) acrylic acid ester content of 7 to 15% by weight. A golf ball material comprising 30 to 70 parts by weight of a lithium or sodium ionomer (B) having a degree of neutralization of a (meth) acrylic acid / (meth) acrylate copolymer of 30 to 80%. (Meth) acrylic acid content of 7 to 15% by weight and (meth) acrylic acid ester content of 7 to 15% by weight by magnesium ion of ethylene / (meth) acrylic acid / (meth) acrylic acid ester copolymer A golf ball material comprising a co-ionized ionomer having a degree of neutralization of 20 to 50% and a degree of neutralization with lithium ions or sodium ions of 15 to 40%. 3. The golf ball material according to claim 1, having a Shore D hardness of 58 or less and a rebound resilience of 60% or more. (Meth) acrylic acid content of 7 to 15% by weight and (meth) acrylic acid ester content of 7 to 15% by weight by magnesium ion of ethylene / (meth) acrylic acid / (meth) acrylic acid ester copolymer A coionized ionomer having a degree of neutralization of 20 to 50% and a degree of neutralization with lithium ions or sodium ions of 15 to 40%.

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