JP2000154256A - Sphere with high specific gravity - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a sphere which can substitute for a high-sepcific-gravity sphere made of lead, a hard metal, or the like by mixing a tungsten powder mainly comprising primary particles with a thermoplastic resin or elastomer in a specified ratio and injection molding the resultant mixture so that the specific gravity of the resultant molded item is a specified value. SOLUTION: A mixture mainly comprising 45-75 vol.% tungsten powder which is obtained by cracking agglomerates occurring in the production process and mainly comprises primary particles and 25-55 vol.% thermoplastic resin or elastomer is molded so that a molded item with a specific gravity of 9-15 is obtained. The use of a biodegradable resin as the thermoplastic resin is environmentally preferable since it gives a sphere which decomposes even when left behind as a bullet or a fishing sinker in a mountain or in the sea. The surface of the sphere may be coated with e.g. a fluororesin, graphite, or molybdenum disulfide to improve the heat resistance or slipperiness. Thus, the spheres can be mass-produced at a high precision.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high specific gravity sphere used for various weights, balancers, sensors, bullets and the like.

[0002]

2. Description of the Related Art Conventionally, spheres used for various weights, balancers, sensors, bullets, etc. are classified according to their specific gravities.
A sphere having a specific gravity of 8 or less is manufactured by header processing of steel or the like, and has been subjected to further post-processing when dimensional accuracy is required. The spheres having a specific gravity of 10 to 11 are manufactured by casting of lead or atomizing method, and the spheres having a specific gravity of 13 to 18.5 are formed of cemented carbide or tungsten (W) based metal alloy manufactured by powder metallurgy. Met.

[0003]

However, the sphere made of steel or the like has a problem that the specific gravity is small, and the sphere using lead has a feature that it is advantageous in cost, but it has a high precision. Is difficult to manufacture and has the problem of lead pollution. Furthermore, spheres made of sintered materials such as the above-mentioned cemented carbide manufactured by powder metallurgy have the advantage of high specific gravity and high accuracy, but because they are manufactured at high temperatures and high pressures, a large amount of energy is required for manufacturing. There was a problem of consuming.

In particular, when the above-mentioned high specific gravity sphere is used as a bullet, lead has a problem of lead pollution, and has a problem that straightness is inferior due to extremely poor sphericity and a hit rate is low. was there. On the other hand, in the case of steel or the like or cemented carbide, there is a problem that the strength (hardness) of the bullet is too large and the barrel is damaged.

Further, in order to increase the flight distance of a lure (pseudo bait) or to enhance the action, a lure with a high specific gravity is incorporated in the lure as a weight, but the weight is high. Therefore, due to the sphericity and weight variation of the sphere, the variation in performance tends to be noticeable at each lure,
In addition, there is a problem that it is difficult to design the lure weight balance and the like.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a high specific gravity sphere which can be used as a substitute for a high specific gravity sphere made of lead, cemented carbide, or the like, and which is highly accurate and can be mass-produced at low cost. The purpose is to do.

[0007]

In order to achieve the above object, a sphere having a high specific gravity according to claim 1 comprises 45 to 75% by volume of tungsten powder and 25 to 55% by volume of a thermoplastic resin or a thermoplast. It is characterized by being formed by injection molding with a specific gravity of 9 to 15 using a mixed raw material mainly containing at least one selected from plastic elastomers.

The sphere having a high specific gravity according to a second aspect is characterized in that, in the first aspect, the tungsten powder is mainly composed of primary particles obtained by crushing agglomeration generated in a process of producing the tungsten powder. It is assumed that.

A high specific gravity sphere according to a third aspect is characterized in that, in the first or second aspect, the thermoplastic resin is a biodegradable resin.

A sphere having a high specific gravity according to a fourth aspect is characterized in that, in the first to third aspects, the surface is coated.

Hereinafter, the present invention will be described in detail. In the present invention, a thermoplastic resin such as nylon, polybutylene terephthalate, polycarbonate, polypropylene, polyethylene, polystyrene, acryl, polyester, polyferrenin sulfide or ABS resin, or various thermoplastic elastomers (styrene, olefin,
A material comprising at least one member selected from the group consisting of vinyl chloride, urethane, ester, amide, fluorine, and ionomer is used. Among these, those composed of at least one selected from nylon, polybutylene terephthalate, polypropylene, polyethylene, polystyrene, polyferrenin sulfide, and various thermoplastic elastomers are preferred. Further, among the above-mentioned thermoplastic resins or thermoplastic elastomers, those composed of two or more types having compatibility with each other are more preferable.

The high specific gravity sphere according to the present invention mainly comprises 45 to 75% by volume of tungsten powder and 25 to 55% by volume of at least one selected from a thermoplastic resin or a thermoplastic elastomer. It is produced by ordinary injection molding using the mixed raw materials so that the specific gravity becomes 9 to 15. As a preferred embodiment of the present invention, a mixed raw material comprising 45 to 75% by volume of tungsten powder and 25 to 55% by volume of at least one selected from a thermoplastic resin or a thermoplastic elastomer is used, It is manufactured by ordinary injection molding so that the specific gravity becomes 9 to 15.

Here, at least one kind selected from a thermoplastic resin or a thermoplastic elastomer is 25% or more.
When the content is less than the volume%, the injection moldability is remarkably reduced and molding becomes difficult, or the dimensional accuracy and weight variation are deteriorated. On the other hand, at least one kind selected from a thermoplastic resin or a thermoplastic elastomer is 55% by volume.
If it exceeds, the specific gravity of the sphere becomes smaller than 9, and it is not suitable for use of a weight or the like as a sphere having a high specific gravity.

More preferably, the sphere has a specific gravity of 11 to 14. If it is used as a substitute for lead as a weight or the like, the specific gravity of the sphere is preferably 11 or more, while at least one selected from a thermoplastic resin or a thermoplastic elastomer for more stable injection molding. In order to contain 30% by volume or more, the specific gravity of the sphere should be 14%.
This is because it is necessary to keep it low.

As the tungsten powder, it is preferable to use one mainly composed of primary particles obtained by crushing agglomeration (secondary particles) generated in the process of producing the tungsten powder. When tungsten powder mainly composed of primary particles obtained by pulverization is used, the filling property is improved, high filling is possible, and high specific gravity can be achieved. Specifically, for example, in the case of a standard tungsten powder, even if the Fischer sub-sieve sizer particle size (FSSS particle size) is 8.8 μm, when the particle size distribution is measured by a laser diffraction method, 50% of the particle size distribution is measured. The cumulative particle size is 25.78 μm, and the tap density is 6.6 g / c.
c (relative density ratio 34%), whereas tungsten powder mainly composed of primary particles obtained by pulverizing the same has a 50% cumulative particle size of 9.57 μm and a tap density of Is 10.0 g / cc (relative density ratio 52
%), Which means that it has a high filling property.

When tungsten powder mainly composed of primary particles obtained by pulverization is used, the kneading property is improved, the viscosity of the injection molding raw material is reduced, and the molding property is improved.

In addition to the tungsten powder and at least one selected from the group consisting of thermoplastic resins and thermoplastic elastomers, the following may be added as required. That is, for example, silane-based or titanium-based coupling materials for improving the bonding strength and wettability between the tungsten powder and the thermoplastic resin, plasticizers and lubricants for improving injection moldability, and other oxidizing agents. Inhibitors and thermal stabilizers.

The high specific gravity sphere of the present invention can be replaced with a high specific gravity sphere made of lead, cemented carbide or the like. Further, since a large amount of tungsten powder is added, a sufficient specific gravity can be ensured, and the shrinkage of the resin during injection molding is reduced, so that high dimensional accuracy and sphericity can be ensured. In addition, since it is formed by injection molding, it is possible to suppress the consumption of energy as compared with the production by the powder metallurgy method and the like, and it is possible to produce a large amount at low cost.

When the sphere having a high specific gravity of the present invention is used for a bullet, the problem of lead pollution is eliminated, and since the sphericity is excellent, straightness is improved and the hit rate is increased. Further, since the strength (hardness) of the bullet can be maintained at an appropriate level, damage to the barrel can be suppressed.

Further, when the high specific gravity sphere of the present invention is used as a weight incorporated in a lure, the dimensional accuracy is high and the weight variation is small, so that the performance variation of each lure is small, and the weight balance of the lure is also reduced. Design becomes easier.

If a biodegradable resin is used as the thermoplastic resin, the biodegradable resin is decomposed even if the sphere having a high specific gravity of the present invention is used as a bullet or lure weight and remains on a mountain or sea. Environmentally preferred.

Further, the surface of the sphere having a high specific gravity may be coated with a coating such as fluororesin, graphite or molybdenum disulfide in order to improve heat resistance and sliding property. Thereby, for example, when this high specific gravity sphere is used for a bullet, the heat resistance against heat generated at the time of firing can be improved. In addition, when the sphere having a high specific gravity is used for a lure weight, a sensor, or the like, the slidability for improving the reactivity can be improved.

[0023]

Next, the present invention will be described specifically. When the particle size distribution is measured by a laser diffraction method, the 50% cumulative particle size is 9.57 μm, and the tap density is 10.0 g / cc.
Tungsten powder mainly composed of primary particles (relative density ratio: 52%) and LLDPE (linear low-density polyethylene) were mixed with 49.7% by volume (95.4% by weight) and 50.3% by volume, respectively. (4.6 wt%), a sphere having a diameter of 5 mm and a theoretical specific gravity of 10.1 was produced by ordinary injection molding. In this case, the kneadability was good and the moldability was good due to the low viscosity. Also,
The resulting sphere had a specific gravity of 10.0 and had high dimensional accuracy and sphericity. The specific gravity of tungsten is 19.
3. The specific gravity of LLDPE is 0.92.

[0024]

As described above, according to the sphere having a high specific gravity according to claim 1, 45 to 75% by volume of tungsten powder and 25 to 55% by volume of a thermoplastic resin or a thermoplastic elastomer are selected. It is formed by injection molding with a specific gravity of 9 to 15 using a mixed raw material mainly composed of at least one or more of the above-mentioned materials. It is highly accurate and can be mass-produced at low cost.

According to the second aspect of the present invention, the tungsten powder is mainly composed of one powder obtained by crushing agglomeration generated in the process of producing the tungsten powder.
Since the particles are composed of the secondary particles, the filling property and the kneading property are improved, so that the specific gravity can be increased and the moldability can be improved.

According to the third aspect of the present invention, since the thermoplastic resin is a biodegradable resin, it is suitable for the environment. According to the fourth aspect of the present invention, since the surface is coated, the heat resistance and the sliding property can be improved.

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[Procedure amendment]

[Submission date] March 13, 2000 (200.3.1)
3)

[Procedure amendment 1]

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[Correction target item name] Claims

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[Claims]

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[Correction target item name] 0007

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[0007]

In order to achieve the above object, a high specific gravity sphere according to claim 1 is obtained by breaking up agglomeration generated in a production process of 45 to 75% by volume.
Using a mixed raw material mainly comprising the obtained tungsten powder mainly composed of primary particles and 25 to 55% by volume of at least one selected from a thermoplastic resin or a thermoplastic elastomer, the specific gravity is 9 to 10%. 15 is formed by injection molding.

[Procedure amendment 3]

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[0009] High density sphere according to claim 2, claim
The invention according to 1, wherein the thermoplastic resin is a biodegradable resin.

[Procedure amendment 5]

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[0010] High density sphere according to claim 3, claim
The invention according to 1 or 2, wherein the surface is coated.

[Procedure amendment 6]

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[0012] The high specific gravity spheres of the present invention can be obtained by breaking up agglomeration generated in a production process of 45 to 75% by volume.
Using a mixed raw material mainly comprising the obtained tungsten powder mainly composed of primary particles and 25 to 55% by volume of at least one selected from a thermoplastic resin or a thermoplastic elastomer, the specific gravity is 9 to 10%. It is manufactured by normal injection molding so that the number of the components becomes 15.

[Procedure amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0015

[Correction method] Change

[Correction contents]

As the tungsten powder, a powder mainly composed of primary particles obtained by crushing agglomeration (secondary particles) generated in the process of producing the tungsten powder is used. When tungsten powder mainly composed of primary particles obtained by pulverization is used, the filling property is improved, high filling is possible, and high specific gravity can be achieved. Specifically, for example, in the case of a standard tungsten powder, even if the Fischer sub-sieve sizer particle size (FSSS particle size) is 8.8 μm, when the particle size distribution is measured by a laser diffraction method, 50% of the particle size distribution is measured. Cumulative particle size is 25.7
8 μm and a tap density of 6.6 g / cc (a relative density ratio of 34%), which is obtained by crushing this.
In the case of tungsten powder mainly composed of primary particles,
The 50% cumulative particle size is 9.57 μm, the tap density is 10.0 g / cc (relative density ratio 52%), and it can be seen that the material has high filling properties.

[Procedure amendment 8]

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[Correction target item name] 0024

[Correction method] Change

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[0024]

As described above, according to the high specific gravity sphere according to the first aspect, the production process of 45 to 75% by volume is performed.
Mainly obtained by breaking up the agglomeration that occurs in
The specific gravity is adjusted to 9 to 15 using a mixed raw material mainly containing tungsten powder composed of primary particles and at least one selected from a thermoplastic resin or a thermoplastic elastomer of 25 to 55% by volume. Since it is formed by injection molding, it can be used as a substitute for a high-density sphere made of lead, cemented carbide, or the like, and can be mass-produced with high accuracy and at low cost.

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In particular, tungsten powder mainly composed of primary particles obtained by crushing agglomeration generated in the process of producing tungsten powder is used.
Because there, in order to improve the filling property and kneadability, moldability becomes good it is possible to achieve high specific gravity.

[Procedure amendment 10]

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[Correction target item name] 0026

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According to the second aspect of the present invention, since the thermoplastic resin is a biodegradable resin, it is suitable for the environment. According to the third aspect of the present invention, since the surface is coated, the heat resistance and the sliding property can be improved.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F42B 12/72 B29C 45/00 // B29C 45/00 C08L 101/00 ZABA B29K 105: 06 505: 00 B29L 31:00 F term (reference) 2B107 JA08 JA31 4F071 AA02 AA15 AA20 AA22 AA31 AA45 AA50 AA54 AA62 AA70 AB06 AH19 BA01 BB05 BC07 BC11 4F206 AA08 AA24 AB11 AB16 AG19 AH81 JA07 4J002 AA011 BB031 BB 001 CN011 DA116

Claims (4)

[Claims] 1. A specific gravity using a mixed raw material mainly comprising 45 to 75% by volume of tungsten powder and 25 to 55% by volume of at least one selected from a thermoplastic resin or a thermoplastic elastomer. Wherein the sphere has a high specific gravity, which is formed by injection molding so that the particle diameter becomes 9 to 15. 2. The high specific gravity sphere according to claim 1, wherein the tungsten powder is mainly composed of primary particles obtained by breaking up agglomeration generated in a process of producing the tungsten powder. 3. The high specific gravity sphere according to claim 1, wherein the thermoplastic resin is a biodegradable resin. 4. A sphere having a high specific gravity according to claim 1, wherein the surface is coated.