JPH09313646A - Golf ball material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a golf ball material having low hardness and high repulsive elasticity and to obtain the golf ball material exhibiting satisfactory performance even if ionomer having a high acid content is not used as a rigid ionomer. SOLUTION: This golf ball material consists of the blend composed of 3 to 70 pts.wt. magnesium ionomer (A) of 10 to 22wt.% in the (meth)acrylic acid content and 40 to 70% in the neutralization degree of the (meth)acrylic acid copolymer and 70 to 30wt.% alkaline metal ionomer (B) of 30 to 80% in the neutralization degree of an ethylene-(meth)acrylic acid-(meth)acrylate copolymer of 3 to 15wt.% in the (meth)acrylic acid content, 10 to 35wt.% in the (meth) acrylate content. The (meth)acrylic acid polymn. component ionized with magnesium of the blend is 3 to 8wt.%, the (meth)acrylic acid polymn. component ionized with an alkaline metal is 1 to 5wt.% and the (meth)acrylate polymer. component is 7 to 18wt.$%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a golf ball material having low hardness and high impact resilience. For more information,
The present invention relates to a golf ball material that is excellent in controllability and can provide a golf ball that is easy to spin.

[0002]

2. Description of the Related Art Various ionomers have been proposed and used as a brook ball cover material because of its excellent durability. Generally, the harder the ionomer is, the more excellent the impact resilience is. The hard ionomer is generally used from the viewpoint of increasing the flight distance of the golf ball. However, golf balls using a hard ionomer as a cover material have dissatisfaction in terms of controllability and shot feeling, so it is proposed to use a soft ionomer by blending it with a hard ionomer, and it has come into practical use. Came.

For example, Reseach Disclosure 27103 (Novemb
1986) discloses the use of blends of soft and hard ionomers in golf ball cover materials. JP-A-1-308577 discloses the use of a blend of a hard ionomer of zinc or sodium and a soft ionomer of zinc or sodium as a golf ball cover material. However, in such a blend system,
There is a drawback that a material having sufficiently high impact resilience cannot be obtained. A similar proposal is proposed in Japanese Patent Laid-Open No. 5-3931 and describes the possibility of using magnesium and lithium ionomers other than zinc and sodium as hard ionomers, but the target is sodium and zinc ionomers. It is limited, and the experimental examples are also limited to these.

In order to make up for the lack of impact resilience as described above,
A proposal using a harder hard ionomer, for example, an ionomer having a high acid content or a lithium ionomer, is disclosed in, for example, JP-A-4-314646 and WO9.
5/00212 and WO95 / 11273, and the latter two proposals disclose the possibility of using magnesium ionomers in addition to sodium, zinc, and lithium ionomers, but specific examples are shown. Absent. When such a harder ionomer is used, impact resilience is improved, but there is a problem that flexibility is slightly sacrificed. Further, ionomers having a high acid content have a high hygroscopic property, so that they easily cause foaming troubles during molding, or have a problem that the molding cycle becomes long because of a low freezing point. It was more desirable to use an ionomer with a lesser content.

In the combination of ionomers specifically disclosed in these prior art documents, when an alkali metal ionomer is selected as a hard ionomer and this is used in combination with a soft ionomer, the impact resilience is generally the phase of both ionomers. Since it shows a value close to the arithmetic mean, it is difficult to obtain a blend that is flexible and has a large impact resilience. When zinc ionomer is selected as the hard ionomer, and when this is combined with a soft alkali metal ionomer, the impact resilience of the zinc ionomer may be slightly higher than the arithmetic mean, but the zinc ionomer has a sufficiently high impact resilience. Since it is not large, it is difficult to obtain a flexible material having a large impact resilience like the above.

[0006]

In view of the above circumstances, the present inventors have made various studies to obtain a material having low hardness and high impact resilience which is desirable as a golf ball material. As a result, when the types of hard ionomer and soft ionomer and their blending ratios, the composition of the blend, etc. are strictly selected, the impact resilience of the blend exceeds the arithmetic mean of those of the raw ionomer, and shows a sufficient value. The present invention has been reached, and the present invention has been reached.

Accordingly, it is an object of the present invention to provide a golf ball material having a low hardness and a high impact resilience. Another object of the present invention is to provide a golf ball material exhibiting sufficient performance without using an ionomer having a high acid content as a hard ionomer.

[0008]

According to the present invention, ethylene having a (meth) acrylic acid content of 10 to 22% by weight is used.
30-70 parts by weight of magnesium ionomer (A) having a degree of neutralization of (meth) acrylic acid copolymer of 40-70%, and (meth) acrylic acid content of 3-15% by weight, (meth) acrylic acid ester From a blend of 70 to 30 parts by weight of an alkali metal ionomer (B) having a neutralization degree of 30 to 80% of an ethylene / (meth) acrylic acid / (meth) acrylic acid ester copolymer having a content of 10 to 35% by weight. 3 to 8% by weight of magnesium ionized (meth) acrylic acid polymerized component and 1 part of alkali metal ionized (meth) acrylic acid polymerized component in the blend.
~ 5 wt%, (meth) acrylic acid ester polymerization component is 7
A golf ball material is provided that comprises a blend that is -18% by weight.

According to the present invention, an ethylene / (meth) acrylic acid copolymer (C) having a (meth) acrylic acid content of 10 to 22% by weight and a (meth) acrylic acid content of 30 to 70% by weight are also contained. 70 to 30 parts by weight of ethylene / (meth) acrylic acid / (meth) acrylic acid ester copolymer (D) having an amount of 3 to 15% by weight and a (meth) acrylic acid ester content of 10 to 35% by weight, A blend obtained by co-ionization with magnesium ions and alkali metal ions, wherein the magnesium ionized (meth) acrylic acid polymerization component in the blend is 3 to 8% by weight, and the alkali metal ionized (meth) acrylic acid is used. 1 polymerization component
~ 5 wt%, (meth) acrylic acid ester polymerization component is 7
A golf ball material is provided that comprises a blend that is -18% by weight.

The golf material used in the present invention preferably has a Shore D hardness of 58 or less and a impact resilience of 60% or less.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The first feature of the first golf ball material of the present invention is to select a specific magnesium ionomer (A) as the hard ionomer, and ethylene (meta) as a base is selected. The acid content of the acrylic acid copolymer is 10 to 22% by weight, preferably 13
-18% by weight, and the degree of neutralization with magnesium ions is 40-70%, preferably 45-65%.

When an alkali metal ionomer or a zinc ionomer is used instead of the magnesium ionomer, the impact resilience is lower than 60% even if the hard ionomer has an acid content and a neutralization degree within the above range. , The desired effect cannot be achieved (Comparative Example 2)
And 3).

In addition, the base polymer ethylene.
If a (meth) acrylic acid copolymer having a (meth) acrylic acid content smaller than the above range is used, it becomes difficult to obtain a blend having a sufficiently large impact resilience, and if the content exceeds the above range. As the hardness increases, the impact resilience does not increase so much, but the balance between flexibility and impact resilience is poor. In addition, magnesium ionomers having a high acid content have a high hygroscopic property, and therefore have a drawback that they easily cause processing troubles. Further, since the ionomer having a high acid content has a low freezing point, there is a drawback that the molding cycle at the time of injection molding takes a long time.

The degree of neutralization in magnesium ionomers is very important in the present invention. In the case of magnesium ionomers, the degree of neutralization that gives the highest hardness, flexural rigidity, impact resilience, etc. is often 30-40%, but blends with sufficiently high impact resilience even with such ionomers. It is difficult to obtain 40 to 7 with low hardness, flexural rigidity and impact resilience.
The present inventors have found that the blend having a neutralization degree of 0% is superior in the impact resilience of the blend.

That is, when the degree of neutralization of the magnesium ionomer is less than 40%, synergistic improvement in the impact resilience cannot be expected, and the impact resilience of the golf ball material becomes less than 60% and the flight distance is reduced. (Comparative Examples 4 and 5).

WO95 / 00212 teaches the use of ionomers having a high acid content as the hard ionomer, but according to the present invention, those having a predetermined degree of neutralization even if the acid content is not so high. If used, a blend with high impact resilience can be obtained. On the contrary, even if the magnesium ionomer has a high acid content and a high rigidity, it is difficult to obtain a blend having a high impact resilience if a magnesium ionomer having a low degree of neutralization is used. If a magnesium ionomer having a degree of neutralization of more than 70% is used, the melt fluidity becomes extremely low due to the high degree of neutralization, so that the blended state with the alkali metal ionomer may deteriorate.

The magnesium ionomer (A) also has a melt flow rate of 0.01 to 20 g / 10 minutes, particularly 0.1 to 1 at 190 ° C. under a load of 2160 g.
0 g / 10 minutes, flexural rigidity 150-500 MPa, especially 200-300 MPa, Shore D hardness 50-7
It is preferable to use 0, especially 55 to 65.

The above magnesium ionomer (A)
The second characteristic is that is combined with a specific ethylene / (meth) acrylic acid / (meth) acrylic acid ester copolymer ionomer (B) in a specific amount ratio.

That is, in the first golf ball material of the present invention, the content of (meth) acrylic acid is 3 to 15% by weight, preferably 5 to 12% by weight, together with the magnesium ionomer (A), (meth). Acrylic ester content is 10-35% by weight, preferably 15-30% by weight
The alkali metal ionomer (B) having a degree of neutralization of the ethylene / (meth) acrylic acid / (meth) acrylic acid ester copolymer of 30 to 80%, preferably 35 to 75% is used.

The alkali metal in the alkali metal ionomer (B) includes lithium, sodium, potassium and the like. Even if a zinc ionomer is used instead of such an alkali metal ionomer, it is difficult to obtain a blend having a large impact resilience. is there.

When a base polymer of the alkali metal ionomer (B) having an acid content lower than the above range is used, the compatibility with the magnesium ionomer (A) is poor, and when the blend is used as a golf ball material, It is not preferable because it is inferior in impact durability and scratch resistance. Further, if the amount is more than the above range, the base polymer pellets are likely to stick to each other, which is not preferable.

On the other hand, if the ester content is less than the above range, it is difficult to obtain a blend having a low hardness due to poor flexibility. On the other hand, if the ester content is more than the above range, it becomes too soft and the pellets are Handling in the state becomes difficult, which is not preferable.

Examples of the above ester include methyl acrylate, ethyl acrylate, isopropyl acrylate,
Examples thereof include n-butyl acrylate, isobutyl acrylate, isooctyl acrylate, methyl methacrylate, ethyl methacrylate, isobutyl methacrylate and the like.

Further, an alkali metal ionomer (B)
If the neutralization degree is less than 30%, it is difficult to obtain a blend having a high impact resilience, and if the neutralization degree exceeds 80%, a good blend is obtained because the melt flow is low. You may not get it.

The alkali metal ionomer (B) also has a melt flow rate of 0.01 to 20 g / 10.
Min, especially 0.1-10 g / 10 min, flexural rigidity 10
It is preferable to use those having a hardness of -100 MPa, especially 20-60 MPa, and a Shore D hardness of 30-50, especially 35-48.

The mixing ratio of the magnesium ionomer (A) and the alkali metal ionomer (B) is (A) 30-.
70 parts by weight, preferably 40 to 60 parts by weight,
(B) is in the range of 30 to 70 parts by weight, preferably 40 to 60 parts by weight (total of 100 parts by weight) and is ionized with magnesium in the blend (meth).
Acrylic acid polymerization component is 3 to 8% by weight, preferably 4 to 7
% By weight, 1-5% by weight of the (meth) acrylic acid polymerization component ionized with an alkali metal, preferably 2-4% by weight, 7-18% by weight of the (meth) acrylic acid ester polymerization component, preferably 8- It is blended so as to be 15% by weight. By blending as described above, a blend having a low hardness and a large impact resilience can be obtained. For example, it is possible to easily obtain a blend having a Shore D hardness of 58 or less, preferably 55 or less and a rebound resilience of 60% or more in a blend of both (a state where no additives are blended).

If the amount ratio of the magnesium ionomer (A) exceeds the above range, the Shore D hardness exceeds 58 and the shot feeling is impaired (Comparative Example 6). on the other hand,
When the amount ratio of the magnesium ionomer (A) is less than the above range, the impact resilience becomes less than 60% and the flight distance is reduced (see Comparative Example 9). When the amount of the (meth) acrylic acid polymerized component ionized with magnesium in the blend is less than the above range, the impact resilience decreases (see Comparative Example 7), while when it exceeds the above range, the Shore D hardness increases. It becomes too unfavorable.

The golf ball material having the same properties as the first golf ball material of the present invention has a (meth) acrylic acid content of 10 to 22% by weight, preferably 13 to 18% by weight of ethylene. (Meth). Acrylic acid copolymer (C) 30
To 70 parts by weight and (meth) acrylic acid content of 3 to 15% by weight, preferably 5 to 12% by weight, (meth) acrylic acid ester content of 10 to 35% by weight, preferably 15 to
30% by weight of ethylene / (meth) acrylic acid / (meth)
Acrylic ester copolymer (D) 70 to 30 parts by weight (the total amount of both is 100 parts by weight) is coionized with magnesium ions and alkali metal ions, and the resulting blend is ionized with magnesium (meth) acrylic acid. Polymerization component is 3 to 8% by weight, preferably 4 to 7% by weight, alkali metal ionized (meth) acrylic acid polymerization component is 1 to 5% by weight, preferably 2 to 4% by weight,
It can also be obtained by adjusting the (meth) acrylic acid ester polymerization component to 7 to 18% by weight, preferably 8 to 15% by weight.

The reason for the numerical limitation in the second golf ball material is the same as that in the first golf ball material, and the Shore D hardness is 58 or less, preferably 55.
Hereinafter, a blend having a repulsion elastic modulus of 60% or more can be easily obtained.

The above copolymers (C) and (D) include
Each has a melt flow rate of 5 to 500 g / 10 minutes,
Particularly, it is preferable to use the one having 10 to 100 g / 10 minutes. As the (meth) acrylic acid ester in the copolymer (D), the same ones as those exemplified in the ionomer (B) can be used.

For co-ionization of the copolymers (C) and (D), various compounds of magnesium and alkali metals such as oxides, hydroxides, carbonates, bicarbonates and fatty acid salts can be used. it can. Co-ionization can be carried out according to a known method for producing a normal ionomer.

In the co-ionization of the copolymers (C) and (D), the highly acidic copolymer (C) is first ionized with magnesium, and then the copolymer (D) is ionized with an alkali metal. However, it is not excluded that the ionization of the copolymer (C) by the alkali metal and the ionization of the copolymer (D) by the magnesium proceed simultaneously.

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 the dual cover, it can be used as a cover material for the outer layer or the inner layer.

The first and second golf ball materials can also be used as one-piece ball materials.

When used as a golf ball material,
Optionally, additives can be blended and used. Examples of such additives include antioxidants, weathering stabilizers, light stabilizers, heat stabilizers, ultraviolet absorbers, lubricants, pigments, dyes,
An inorganic filler etc. can be illustrated.

[0036]

EXAMPLES The present invention will be described with reference to Examples and Comparative Examples. The physical property values in Examples and Comparative Examples were measured by the following methods. -MFR: based on JIS K7210, temperature 190 ° C,
Load 2160 g-Hardness (Shore D): Compliant with ASTM D2240-Flexural rigidity: Compliant with JIS K7106-Rebound resilience: Compliant with JIS K6301 Contents of ionomer resin and acid copolymer used in the following Examples and Comparative Examples Are shown in Tables 1 and 2.

[0037]

[Table 1]

[0038]

[Table 2]

Example 1 As a hard ionomer, ionomer resin 1 (54%-
Mg), ionomer resin 8 as a soft ionomer
(52% -Na) was selected, and this was dry blended at a weight ratio of 50:50 and supplied to a single-screw extruder (screw diameter 40 mm, L / D = 28) at a melting temperature of 20.
Melt kneading was carried out under the conditions of 0 ° C. and screw rotation speed of 40 rpm. The obtained resin composition was hot press molded into a predetermined shape, and various physical properties were evaluated by the methods described above. The results are shown in Table 3.

Examples 2 to 4 and Comparative Examples 1 to 6 As in Example 1, various hard ionomers and various soft ionomers were melt-kneaded at the weight ratios shown in Table 3 and the physical properties of the blends were examined. The results are shown in Table 3.

In order to clearly show the effect of the present invention, description will be made with reference to FIGS. FIG. 1 shows the relationship between the impact resilience and hardness of the [hard ionomer / soft ionomer = 50/50 blend] obtained in Examples 1 and 2 and Comparative Examples 1 to 3. In this figure, the left end of the broken line shows the data of the soft ionomer and the right end shows the data of the hard ionomer alone, and the middle bending point is the data of the blend. Hard Mg
In Examples 1 and 2 using the ionomer, it was found that the physical properties of the blend exceeded the arithmetical mean of the raw material polymer, and had a high impact resilience comparable to that of the hard ionomer even though the blend was softened with the soft ionomer. .

On the other hand, N is used as a hard ionomer.
In Comparative Examples 1 and 2 using the a-type or Li-type ionomer, the physical properties of the blends were slightly lower than the arithmetic average of the raw polymer, and the impact resilience (60% or more) targeted by the present inventors was obtained. ) Did not reach. In Comparative Example 3 in which the Zn ionomer was used as the hard ionomer, the decrease in impact resilience due to blending was not so large, but since the Zn ionomer originally had a low impact resilience,
This too did not reach the goal.

FIG. 2 shows the results obtained in Examples 3 and 4 and Comparative Examples 4 and 5 [hard Mg ionomer / soft Na ionomer =
50/50 blend] shows the relationship between impact resilience and hardness. In Examples 3 and 4, since the Mg ionomer having a sufficiently high degree of neutralization is used, the physical properties of the blend are those of Example 1
Although it exceeds the arithmetic mean in the same manner as in Example 1, since the neutralization degree of Mg ionomer is low in Comparative Examples 4 and 5, the impact resilience of the blend reaches the target value even though it shows high impact resilience by itself. Did not reach.

Example 5 Acid copolymer 1 as a hard base resin and acid copolymer 2 as a soft base resin were dry-blended at a weight ratio of 50:50, and a pent type uniaxial was used together with a Mg ion source and a Na ion source. Screw extruder (screw diameter 65mm, L /
D = 33), and melt-kneaded under the conditions of a melting temperature of 250 ° C. and a screw rotation speed of 35 rpm to form a Mg / Na binary ionomer (target neutralization degree: 35% -Mg, 25% -N).
a) was obtained. The obtained ionomer was hot press molded into a predetermined shape, and various physical properties were evaluated. The results are shown in Table 4.

Comparative Examples 7 to 9 As in Example 5, acid copolymer 1 and acid copolymer 2 are shown in Table 4.
The mixture was mixed in the weight ratio shown in 1 and neutralized with a Mg ion source and a Na ion source. The physical property evaluation results are shown in Table 4.

The influence of the degree of neutralization and the weight ratio of the base resin in the present invention will be described with reference to FIG. In Example 5, since the neutralization degree and the weight ratio of the base resin are within the proper range found by the present inventors, the target impact resilience (60% or more) and hardness (58 or less) are significantly increased. It is higher. In Comparative Example 7, the impact resilience did not reach the target because the degree of neutralization of Mg was slightly low. In Comparative Example 8, the degree of neutralization was proper, but the hardness did not fall within the target because the weight ratio of the hard base resin was too high. On the contrary, Comparative Example 9
Then, the blending ratio of the soft base resin was too high and the impact resilience was insufficient.

[0047]

[Table 3]

[0048]

[Table 4]

[0049]

According to the present invention, a golf ball material having a low hardness and a large impact resilience can be easily provided.
A golf ball using such a material has good spin, excellent controllability, and excellent shot feeling.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the impact resilience and hardness of the hard ionomer / soft ionomer blends obtained in Examples 1 and 2 and Comparative Examples 1 to 3.

FIG. 2 is a graph showing the relationship between the impact resilience and hardness of the hard ionomer / soft ionomer blends obtained in Examples 3 and 4 and Comparative Examples 4 and 5.

FIG. 3 is a graph showing the relationship between the impact resilience and hardness of the coionized products obtained in Example 5 and Comparative Examples 7 to 9.

Claims (3)

[Claims] 1. A (meth) acrylic acid content of 10 to 22.
Magnesium ionomer (A) 3 having a degree of neutralization of 40% to 70% by weight of ethylene / (meth) acrylic acid copolymer
0 to 70 parts by weight and (meth) acrylic acid content of 3 to
15% by weight, (meth) acrylate content of 10
To 35% by weight of ethylene / (meth) acrylic acid / (meth) acrylic acid ester copolymer having a neutralization degree of 30 to 80
% Alkali metal ionomer (B) 70 to 30 parts by weight of the blend, wherein the magnesium ionized (meth) acrylic acid polymer component in the blend is 3 to 8%.
A golf ball material comprising a blend of 1% by weight, 1 to 5% by weight of an alkali metal ionized (meth) acrylic acid polymerization component, and 7 to 18% by weight of a (meth) acrylic acid ester polymerization component. 2. The (meth) acrylic acid content is 10 to 22.
Wt% ethylene / (meth) acrylic acid copolymer (C)
30-70% by weight and (meth) acrylic acid content of 3
~ 15 wt%, (meth) acrylate content of 1
A blend obtained by co-ionizing 70 to 30 parts by weight of an ethylene / (meth) acrylic acid / (meth) acrylic acid ester copolymer (D) of 0 to 35% by weight with a magnesium ion and an alkali metal ion, Magnesium ionized (meth) acrylic acid polymerized component in the blend is 3 to 8% by weight, alkali metal ionized (meth) acrylic acid polymerized component is 1 to 5% by weight, (meth)
A golf ball material comprising a blend having an acrylic acid ester polymerization component of 7 to 18% by weight. 3. The golf ball material according to claim 1, wherein the Shore D hardness of the blend is 58 or less and the impact resilience is 60% or more.