JPH11246679A - Polishing material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing material having excellent polishing property, wearing resistance and moldability and having a prolonged using life. SOLUTION: This polishing material is produced by comprising (a) a polyethylene having 0.05-3 g/10 min melt index (MFR2 ) at 190 deg.C under 2.16 Kg load and a ratio (MFR10 /MFR2 ) of a melt index MFR10 to the former melt index MFR2 of <=15, (b) a polyethylene having 1.5-3.5 dl/g intrinsic viscosity [η] in a decalin solvent at 135 deg.C and a ratio of (MFR10 /MFR2 ) of the melt index MFR10 to the melt index MFR2 of <=15, (c) a polyethylene having 0.05-3 g/10 min melt index (MFR2 ) and <=8 molecular weight distribution (Mw/Mn) by gel permeation chromatography or (d) a polyethylene having 1.5-3.5 dl/g intrinsic viscosity [η] in a decalin solvent at 135 deg.C and <=8 molecular weight distribution (Mw/Mn) by gel permeation chromatography as principal components to obtain the subject polishing material having excellent polishing property, wearing resistance and moldability and having a prolonged using life.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention belongs to the technical field of polishing materials, and more particularly to a polishing material suitable for polishing the surface of metal products such as pachinko balls and ball bearings.

[0002]

2. Description of the Related Art For example, in the case of a pachinko ball, if rust or dirt adheres to the surface, it may affect the ball-out rate of pachinko games, or the ball may be clogged in a passage inside the pachinko machine. Polishing (work for polishing balls) to remove dirt and dirt is performed.

[0003] The polishing material used for polishing the pachinko balls can of course be polished satisfactorily, furthermore, it does not damage the surface of the pachinko balls, and no abrasive powder is generated from the polishing material. (Good abrasion resistance) was also required. In addition, amusement shops also demand that the abrasive material have a long life, and manufacturers demand that the moldability be good.

[0004] The performance or properties such as good abrasion, not damaging the surface of the material to be polished, good abrasion resistance, long life, and excellent moldability are the polishing materials of pachinko balls. In addition to this, there has been a demand for polishing materials for other metal products. Conventionally, nylon pellets have been used as polishing materials for pachinko balls, game coins, and the like. However, due to the high hardness of nylon, the contact area between the nylon pellets and metal products such as pachinko balls was small, and it was difficult to sufficiently polish the nylon. Nylon does not always have good abrasion resistance and also has high hygroscopicity. Therefore, abrasion resistance is further deteriorated by absorbing the mixed water. As a result, the amount of abrasion powder generated increased over time, and the life of the pellets was not necessarily long.

For this reason, polishing materials have been proposed to replace the nylon resin having the above-mentioned disadvantages. For example, Japanese Patent Publication No. 2625168 discloses a polishing material having a low molecular weight polyolefin and a low molecular weight polyolefin.
The intrinsic viscosity [η] measured in a decalin solvent at 35 ° C. is 1
An abrasive material comprising a polyolefin composition comprising 0 to 40 dl / g ultra-high molecular weight polyolefin is disclosed.

However, according to the findings of the present inventors, although the ultrahigh molecular weight polyolefin itself disclosed in Japanese Patent Publication No. 2625168 is excellent in abrasion resistance, the polyolefin composition containing the same does not allow separation between components. Liable to occur, and there was still a problem with long-term durability. Particularly, in order to produce an ultrahigh molecular weight polyolefin having an intrinsic viscosity [η] of 15 dl / g or more, a polymerization condition in which hydrogen as a molecular weight regulator is not added is employed, but ordinary polymerization advantageous for catalytic activity is employed. At a temperature (70 ° C. or higher), the high molecular weight was still insufficient. Therefore, below 60 ° C, sometimes 5
It was necessary to employ a low polymerization temperature of 0 ° C. or less, and there was a disadvantage that the productivity of the polymer was low.

[0007]

BACKGROUND OF THE INVENTION The present inventors have conducted intensive studies with the aim of solving the above-mentioned disadvantages of the conventional polishing material. As a result, a polishing material comprising a single-component polyethylene having specific physical properties has been obtained. No exfoliation phenomenon and excellent durability and abrasion resistance were found, and the present invention was completed.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a polishing material which is excellent in abrasiveness, abrasion resistance and moldability and has a long life.

[0009]

As a means for solving the above-mentioned problems, the polishing material according to any one of claims 1 to 5 can be employed. That is, the polishing material according to claim 1 has a melting index MF at 190 ° C. and a load of 2.16 kg.
R ₂ is 0.05 to 3 g / 10 minutes, 190 ° C., load 1
The ratio MFR ₁₀ / MFR ₂ and melt index MFR ₁₀ under 0kg said melt index MFR ₂ is mainly composed of polyethylene 15 or less.

[0010] The polishing material according to claim 2 has a
The intrinsic viscosity [η] measured in a Karin solvent is 1.5 to 3.
In the range of 5 dl / g at 190 ° C under a load of 10 kg
Melting index MFR_TenAt 190 ° C under a load of 2.16 kg
Melting index MFR_Two MFR with _Ten/ MFR_Two Is 15 or less
Polyethylene is the main component.

[0011] The polishing material according to claim 3 is a material having a load of 190 ° C.
Melt index MFR under 2.16 kg weight _Two Is 0.05-3g
/ 10 min, and gel permeation chromatography
Of polyethylene having a molecular weight distribution Mw / Mn of 8 or less
The main component. The polishing material according to claim 4 is 135.
Intrinsic viscosity [η] measured in decalin solvent at 1.5 ° C. is 1.5
~ 3.5 dl / g, gel permeation
Chromatographic molecular weight distribution Mw / Mn of 8 or less
As a main component.

A polishing material according to a fifth aspect is characterized in that the polishing material according to any one of the first to fourth aspects is formed into a spherical, rugby ball, disk, elliptical or columnar compact. .

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The polishing material of the present invention, that is, polyethylene, which is a main component of the polishing material according to the first to fifth aspects, is different from nylon in that it is not excessively high in hardness and is moderate in hardness. It has good adhesion to the material (metal product) and does not absorb moisture due to the moisture attached to the surface of the material to be polished, so there is little possibility that the abrasion resistance is reduced or the life of the polishing material is shortened. .

The reason why the melting index MFR ₂ of the polyethylene is 0.05 to 3 g / 10 min in the abrasive material according to the first aspect is to ensure good abrasiveness and abrasion resistance. That is, the melting index MFR ₂ is 0.05 g.
If it is less than / 10 minutes, the polishing material tends to be too hard and the polishing property tends to be poor, and the melt index MFR ₂ is 3 g / 1.
If the time exceeds 0 minutes, the molecular weight is low, so that abrasion resistance is poor and abrasion powder may be generated.

Further, the melting index MFR ₁₀ and the melting index MFR
_If the ratio MFR ₁₀ / MFR ₂ to ₂ exceeds 15, the melt viscosity will be low and the moldability will be good, but the abrasion resistance as an abrasive will tend to be poor due to the wide molecular weight distribution. Not preferred. Therefore, the melting index MFR ₂
There By mainly the ratio MFR ₁₀ / MFR ₂ is 15 or less polyethylene 0.05 to 3 g / 10 min, and a melt index MFR ₁₀ between the melt index MFR _2, abrasive, wear resistance and It is possible to obtain a polishing material having excellent moldability and a long life.

The melting index MF according to claim 1
The limiting viscosity [η] measured in a decalin solvent at 135 ° C. according to claim ₂ is 1.5 to 3.5 dl / instead of the condition that R ₂ is in the range of 0.05 to 3 g / 10 minutes. Even if the condition of within the range of g is used, it is possible to define a polyethylene exhibiting excellent properties as a polishing material.

When the intrinsic viscosity [η] in the decalin solvent at 135 ° C. is specified, the intrinsic viscosity [η] is 3.5.
If it exceeds dl / g, the polishing material tends to be too hard and the polishing performance tends to be poor, and the intrinsic viscosity [η] is 1.5 dl / g.
If the amount is less than g, the molecular weight is low, so that the abrasion resistance is poor and abrasion powder may be generated. Moreover, the good when the ratio MFR ₁₀ / MFR ₂ of 15 or less and a melt index MFR ₁₀ between melt index MFR ₂ is as described above. Therefore, the abrasive material defined in claim 2 has excellent abrasiveness, abrasion resistance and moldability, and has a long life.

Alternatively, instead of the condition that the ratio MFR ₁₀ / MFR ₂ of the melting index MFR ₁₀ to the melting index MFR ₂ is set to 15 or less, the molecular weight distribution Mw by gel permeation chromatography according to claim 3. /
Even if the condition that Mn is 8 or less is used, it is possible to define a polyethylene exhibiting excellent properties as a polishing material.
Here, Mw represents a weight average molecular weight, and Mn represents a number average molecular weight.

The melting index MFR ₂ is 0.05 to 3 g / 10
As described above, a good polishing material can be obtained in the range of minutes. Further, when the molecular weight distribution Mw / Mn by gel permeation chromatography exceeds 8, the melt viscosity is lowered and the moldability is improved, but the abrasion resistance as a polishing material tends to be inferior due to the wide molecular weight distribution. Is not preferred. Therefore, even with the configuration according to the third aspect, a polishing material having excellent polishing properties, abrasion resistance, and moldability and having a long life can be obtained.

Further, when the intrinsic viscosity [η] measured in a decalin solvent at 135 ° C. is in the range of 1.5 to 3.5 dl / g, and the molecular weight distribution Mw / Mn by gel permeation chromatography is 8 or less. As described above, good polyethylene is used as a polishing material. Therefore, the polishing material according to the fourth aspect provides a polishing material having excellent polishing properties, abrasion resistance and molding workability and a long life.

In the first to fourth aspects, the term "mainly composed of polyethylene" means that, for example, an inorganic filler, an antistatic agent, a surface property improving agent, a deterioration preventing agent and the like, which will be described later, may be added. Yes, it goes without saying that 100% of polyethylene may be used. The polyethylene of the present invention
It is selected from high density polyethylene, linear low density polyethylene and high pressure low density polyethylene.

The high-density polyethylene and the linear low-density polyethylene are produced using various transition metal catalysts.
For example, a catalyst (Ziegler type catalyst) formed from a highly active titanium catalyst component containing magnesium, titanium and halogen as essential components and an organic aluminum compound catalyst component,
Chromium catalyst containing chromium trioxide as an essential component, or IVB containing a ligand having a cyclopentadienyl skeleton
It is obtained by polymerizing ethylene or copolymerizing ethylene and an α-olefin in the presence of a catalyst formed from a metallocene catalyst component having a group III transition metal compound as an essential component and an organoaluminum compound catalyst component.

As the method of the polymerization reaction, any method may be used as long as the above physical properties are satisfied, and any of a slurry method, a solution method and a gas phase method can be adopted. The polymerization may be one-stage polymerization performed under one polymerization condition or multi-stage polymerization performed under two or more polymerization conditions.

When the copolymerization is carried out, α-olefins having 3 to 20 carbon atoms, for example, propylene, 1-
Butene, 1-hexene, 4-methyl-1-pentene, 1
-Octene, 1-decene and the like. In the case of high-density polyethylene, the content of α-olefin in the copolymer is generally 0.02 to 2 mol%, and the density is 0.1%.
940-0.970 g / cm ³ is obtained. In the case of linear low-density polyethylene, the content of α-olefin is generally 1 to 20 mol%, and the density is 0.910 to 0.1.
935 g / cm ³ are obtained.

The high-pressure low-density polyethylene is generally produced by subjecting ethylene to high-pressure radical polymerization at a temperature of 200 to 300 ° C. and a pressure of 1,000 to 2,000 atm. Thus, a density of 0.910 to 0.93
A high-pressure low-density polyethylene of 5 g / cm ³ is obtained.

Although these polishing materials contain polyethylene as a main component, for example, an inorganic filler, an antistatic agent, a surface property improving agent, a deterioration preventing agent and the like can be added. Examples of the inorganic filler include oxides such as aluminum oxide, silicon oxide and titanium oxide, hydroxides such as aluminum hydroxide and magnesium hydroxide, carbonates such as magnesium carbonate, calcium carbonate and zinc carbonate, calcium sulfate, and sulfuric acid. Sulfates such as barium, sodium silicate, magnesium silicate, aluminum silicate, silicates such as aluminosilicate, or clay, talc, mica, kaolin, glass and the like, and when these inorganic materials are added, In some cases, the polishing property is improved. The inorganic filler is not limited to these, and may be any filler that can be filled into polyethylene. However, in order not to damage the surface of the metal product, it is necessary that the hardness is lower than that of the metal product, and it is preferable that the hardness is selected according to the metal product as the material to be polished. If the particle size of the inorganic filler is large, the strength of the polishing material may decrease around the inorganic filler. Therefore, the particle size is preferably as small as possible, for example, 100 μm or less, and preferably 0.5 to 60 μm. When the inorganic filler is compounded, if the amount is too large, the strength of the polishing material may be reduced. If the amount is too small, the effect of the inorganic filler cannot be expected. Therefore, the content in the polishing material is 20% by weight. %, Preferably in the range of 2 to 15% by weight.

The polishing material repeatedly contacts the metal product,
In addition, since the polishing materials are repeatedly contacted with each other, there is a high possibility of being charged. Therefore, the addition of an antistatic agent is effective. As the antistatic agent, for example, a known nonionic surfactant,
Anionic surfactants, cationic surfactants, amphoteric surfactants and antistatic resins can be used. To give a specific example, as a nonionic surfactant,
For example, glycerin fatty acid ester, sorbitan fatty acid ester, propylene glycol fatty acid ester, pentaerythritol fatty acid ester, polyglycerin fatty acid ester, polyoxyethylene glycerin fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyethylene glycol fatty acid ester, polypropylene glycol fatty acid ester, polyoxy Examples of anionic surfactants such as ethylene alkyl phenyl ether, N, N-bis (2-hydroxyethyl) aliphatic amine, and condensation products of fatty acids and diethanolamine include alkyl sulfonates, alkyl benzene sulfonates, and alkali naphthalenes. Sulfonate, sodium alkyl sulfosuccinate, alkyl sulfate, polyoxyethylene alkyl Examples of cationic surfactants such as ruphosphate and the like include dimethylalkylammonium chloride and choline ester chloride of linear fatty acid, and examples of amphoteric surfactants include N-acyl sarcosinate and the like. Examples of the conductive resin include a polyvinylbenzene-type cationic resin and a polyacrylic-acid-type cationic resin. The good content of the antistatic agent in the polishing material depends on the type of the antistatic agent, but is about 0.1 to 5% by weight.

A conductive material such as carbon black, carbon fiber or metal powder may be added in place of or together with the antistatic agent. In order to improve the surface properties of the polishing material, particularly the slidability, for example, a fluororesin such as ethylene tetrafluoride-propylene hexafluoride copolymer and a slidability improver such as molybdenum sulfide can be added. The slidability improver is preferably in the form of powder, and the particle size is 0.05 to 10%.
0 μm, particularly preferably 0.5 to 60 μm. The compounding ratio with respect to the polyethylene varies depending on the type of the slidability improving agent, but is generally 5 to 3 parts per 100 parts by weight of the polyethylene.
0 parts by weight is an appropriate amount.

The anti-deterioration agent is added for the purpose of preventing oxidative deterioration during molding or storage of polyethylene or a blend of polyethylene and various additives. Suitable for such purposes include butylated hydroxytoluene, 4-hydroxymethyl-2,6-di-t-butylphenol, 2-6-di-t-butyl-4-ethylphenol, n-octadecyl-β-. (4'-hydroxy-3 ', 5'-di-t-butylphenyl) propionate, tocopherol, 2,2'-methylenebis (4-methyl-6-t-butylphenol), 2,2'-methylenebis (4- Ethyl-6-t-butylphenol),
4,4'-methylenebis (2,6-di-t-butylphenol), 4,4'-butylidenebis (6-t-butyl-m-cresol), 4,4'-thiobis (6-t-butyl-m -Cresol), N, N'-hexamethylenebis (3,5-di-t-butyl-4-hydroxyhydrocinnamide), 3,5-di-t-butyl-4-hydroxybenzylphosphonic acid monoethyl ester Calcium salt,
2,2'-oxamidobis [ethyl 3- (3,5-di-
Butyl-4-hydroxyphenyl) propionate],
2,2′-ethylidenebis (4,6-di-t-butylphenol), 1,1,3-tris (2-methyl-4-hydroxy-5-t-butylphenylbutane), 1,3
5-trimethyl-2,4,6-tris (3,5-di-t
-Butyl-4-hydroxybenzyl) benzene, tetrakis [methylene-3- (3 ', 5'-di-t-butyl-
4'-hydroxyphenyl) propionate] methane,
2,2′-methylenebis [6- (1-methylcyclohexyl) -p-cresol], bis [3,3′-bis (4′-hydroxy-3′-t-butylphenyl) butanoic acid] glycol ester, Bis [2- (1,1-dimethylethyl) -6-, 4-benzenedicarboxylate
[[3- (1,1-dimethylethyl) -2-hydroxy-5-methylphenyl] methyl] -4-methylphenyl] ester, N, N-bis {3- (3,5-di-t-
Butyl-4-hydroxyphenyl) propionylhydrazine, 1,3,5-tris (3 ′, 5′-di-tert-butyl-4′-hydroxybenzyl) -s-triazine-
2,4,6 (1H, 3H, 5H) -trione, 1,3
5-tris (4-t-butyl-3-hydroxy-2,6
-Dimethylbenzyl) -1,3,5-triazine-2,
Phenolic antioxidants such as 4,6- (1H, 3H, 5H) trione, tris (mixed, mono and dinonylphenyl) phosphite, disteryl allylpentaerythritol diphosphate, tris (2,4-di -T
-Butylphenyl) phosphite, 4,4'-butylidene-bis (3-methyl-6-tert-butylphenyl-di-
Tridecyl phosphite), 1,1,3-tris (2-
Methyl-4-di-tridecylphosphite-5-t-butylphenyl) butane, tetrakis (2,4-di-t-butylphenyl) 4,4′-biphenylenediphosphinate, cyclic neopentanetetraylbis ( 2,
4-di-t-butylphenylphosphite), cyclic butylethylpropanediol, 2,4,6-tri-t-butylphenylphosphite, tris- [2-
(2,4,8,10-Tetrabutyl-5,7-dioxa-6-phospho-di-benzo {a, c} cycloheptene-
Phosphorus antioxidants such as 6-yl-oxy) ethyl] amine and bis- [2-methyl-4,6-bis- (1,1-dimethylethyl) phenyl] ethyl phosphite;
Sulfuric antioxidants such as dilauryl 3'-thiopropionate, dimyristyl 3,3'-thiodipropionate, and disterial 3,3'-thiopropionate, or metal salts of higher fatty acids, ie, stearic acid, oleic acid, lauric acid Metal salts of higher fatty acids such as acids, palmitic acid and behenic acid such as aluminum, calcium, magnesium, zinc and lithium are used. Specific examples of metal salts of higher fatty acids include aluminum stearate, calcium stearate, magnesium stearate, zinc stearate, lithium stearate, calcium oleate, zinc oleate, calcium laurate, zinc laurate, magnesium palmitate , Barium behenate, calcium 12-hydroxystearate and the like. The mixing ratio of these deterioration inhibitors to polyethylene varies depending on the type, but is usually preferably 0.05 to 0.2 parts by weight based on 100 parts by weight of polyethylene.

Further, in addition to these inorganic fillers, antistatic agents, surface property improving agents and deterioration preventing agents, polishing materials include ultraviolet absorbers, light stabilizers, pigments, flame retardants, peroxides and the like. Compounding agents usually added to polyethylene can be added. The abrasive material according to any one of the first to fourth aspects is used in the form of pellets obtained by blending the above-mentioned additive with the above-mentioned polyethylene, for example, by extrusion molding. The shape of the abrasive material is not limited and may be arbitrary, for example, spherical as described in claim 5,
A shape having a curved surface such as a rugby ball shape, a disc shape, an elliptical disc shape, and a column shape is desirable.

[0031]

Next, embodiments of the present invention will be described more specifically with reference to some examples of the present invention. (1) Preparation of Catalyst Four types of solid catalyst components (A), (B), (C) and (D) containing titanium, magnesium and chlorine atoms as main components were prepared. Using each of the obtained solid catalyst components, polyethylene was synthesized. A metallocene catalyst was used for the synthesis of some polyethylene. (2) Synthesis of polyethylene and its physical properties Synthesis of PE1 n-hexane was continuously introduced as a polymerization solvent, solid catalyst component (A) and triethylaluminum were continuously introduced as a catalyst, and the polymerization temperature was set at 85 ° C. 8kg / c
polymerization while supplying ethylene, hydrogen and a small amount of 1-butene so as to maintain m ² , high-density polyethylene (PE1)
Was synthesized. The hydrogen was added by an amount confirmed by experiments in advance as MFR ₂ of the target is obtained.

The resulting polyethylene (PE1) was 19
Melting index MFR ₂ under 0 ° C. and 2.16 kg load is 1.1
g / 10 minutes, intrinsic viscosity [η] measured in a decalin solvent at 135 ° C. is 1.9 dl / g, 190 ° C., load 10 kg
Ratio MFR between lower melting index MFR ₁₀ and melting index MFR _2
10 / MFR ₂ is 9, a gel permeation chromatography molecular weight distribution Mw / Mn 5 by, density 0.95
It was 1 g / cm ³ . Synthesis of PE2 PE2 was synthesized in the same manner as in the synthesis of PE1, except that a small amount of propylene was added instead of 1-butene using the solid catalyst component (B). The obtained polyethylene (PE2)
Are as shown in Table 1. Synthesis of PE3 Using the solid catalyst component (A), PE3 was synthesized in the same manner as in the synthesis of PE1. Physical properties of the obtained polyethylene (PE3) are as shown in Table 1. Synthesis of PE4 Toluene was used as a polymerization solvent, dicyclopentadienyl zirconium dichloride and methylaluminoxane were used as catalysts, and 1-octene was used as a comonomer. The polymerization was performed at a polymerization temperature of 70 ° C. while supplying ethylene, hydrogen and a comonomer. Physical properties of the obtained polyethylene (PE4) are as shown in Table 1. Synthesis of PE5 n-Hexane as a solvent, solid catalyst component (C) and triethylaluminum as a catalyst were continuously introduced into a first-stage polymerization tank, and ethylene, hydrogen and a small amount of ethylene were mixed at a polymerization temperature set at 85 ° C. Polymerization was performed while 1-butene was supplied to obtain polyethylene having an MFR ₂ of 30 g / 10 min.
After the polyethylene slurry was depressurized in the intermediate tank, it was continuously introduced into the second polymerization tank. In the second-stage polymerization tank, polymerization was continued while supplying ethylene and hydrogen at a temperature of 75 ° C. so that the polymerization amount became the same as that in the first stage. Table 1 shows the physical properties of the obtained polyethylene (PE5).
As shown in FIG. Synthesis of PE6 Except that solid catalyst component (D) was used as the catalyst component,
Polymerization was carried out in the same manner as in the synthesis of No. 5 to synthesize polyethylene (PE6). However, the MF of the polyethylene obtained in the first stage
R ₂ was 500g / 10 minutes. Polyethylene (PE
Physical properties of 6) are as shown in Table 1. Synthesis of PE7 PE7 was synthesized in the same manner as in the synthesis of PE1, except that the solid catalyst component (D) was used as the catalyst component and the polymerization temperature was 75 ° C. Physical properties of the obtained polyethylene (PE7) are as shown in Table 1. (3) Production of polishing material 0.2 parts of calcium stearate and n-octadecyl-β- (4′-hydroxy-3 ′, 5′-di-) were added to the polyethylene (PE1 to PE7) synthesized above.
t-butylphenyl) propionate (Irganox1076)
0.05 parts and 0.10 parts of tris (2,4-di-t-butylphenyl) phosphite (Irgafos168) were added, and the strands were extruded by extrusion molding.
It was cut so as to have a column shape of 02 g. Pellets obtained from polyethylene (PE1 to PE4) were used as abrasive materials (hereinafter referred to as K1 to K4) in Examples 1 to 4 described later, and pellets obtained from polyethylene (PE5 to PE7) were used in Comparative Examples 1 to 4 described later. It is assumed that the polishing material is No. 3 (the polishing materials are K5 to K7, respectively). (4) Evaluation method of abrasive material Abrasive materials K1 to K6 produced in the above item (3) and a commercially available abrasive material for nylon pellets (P
Using A1), a wear amount measurement and a polishing experiment using a pachinko ball were performed. The polishing material K7 was not subjected to the measurement of abrasion amount and the polishing experiment because melt fracture occurred during extrusion molding and pellets having good appearance were not obtained.

The amount of wear was measured by measuring a volume of 650 ml and a diameter of 75 m.
m, 700 g of pachinko balls (about 5.5 g each) and 70 g of abrasive material are placed in a stainless steel cylindrical container having a length of 175 mm.
Spin at 70 rpm and stir for 15 hours and 1
The powder generated after 05 hours was collected, weighed, and evaluated by dividing by the weight of the abrasive material.

In the polishing experiment using a pachinko ball washer, a pachinko ball and a polishing material were charged under the conditions according to the operation manual of the silver cleaner using BL-500 manufactured by Silver Denken Co., Ltd., and polishing was performed for 8 hours. This was repeated 10 times and visually evaluated. [Examples 1 to 4 and Comparative Examples 1 to 4] Table 1 summarizes the results of evaluation experiments performed using each polishing material.

[0035]

[Table 1]

As is clear from the results of the comparative experiments shown in Table 1, the abrasive materials of Examples 1 to 4 all have a small amount of abrasion, have good abrasiveness in a pachinko ball washer, and generate abrasion powder. There was no. The abrasive material of Comparative Example 1 had an extremely large amount of abrasion (measurement of the amount of abrasion was completed within 15 hours), and although abrasion was good in a pachinko ball washer, abrasion powder was generated.

The abrasive material of Comparative Example 2 had a large amount of abrasion and had good abrasive properties in a pachinko ball washer, but generated abrasion powder. The abrasive material of Comparative Example 4 had a small initial wear amount (about 15 hours from the start), but generated a large amount of wear powder after 105 hours. It is considered that this is because nylon absorbs moisture due to moisture in the air and the wear resistance is reduced. Further, in the polishing test using a pachinko ball cleaning machine, contamination was observed on the pachinko ball surface, and there was a problem in polishing.

From the above, it can be confirmed that the abrasive materials of Examples 1 to 4 are excellent in abrasiveness, abrasion resistance and moldability, and have a long life. As described above, specific embodiments of the present invention have been described with reference to the examples. However, the present invention is not limited to these examples, and may be variously implemented without departing from the gist of the present invention. Needless to say. For example, in the above embodiment, the polishing material intended for pachinko balls is taken as an example, but the polishing material of the present invention is not limited to pachinko balls, for example, ball bearings, coin-shaped metal pieces, and other metal products. Needless to say, it can be used as an abrasive material.

[0039]

As is clear from the above description,
The abrasive material of the present invention is excellent in abrasiveness, abrasion resistance and molding workability, and has a long life.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshiaki Takahashi 2- 25-10 Hatchobori, Chuo-ku, Tokyo Maruzen Polymer Co., Ltd. (72) Inventor Mitsunori Nakanishi 2-25-10 Hatchobori, Chuo-ku, Tokyo Maruzen Polymer (72) Inventor Tetsuya Iizuka 439 Kamo, Ichihara-shi, Chiba

Claims (5)

[Claims] 1. A melt index MFR ₂ under a load of 2.16 kg at 190 ° C. of 0.05 to 3 g / 10 min.
The melt index MF and melt index MFR ₁₀ under load 10kg
A polishing material mainly composed of polyethylene having a ratio MFR ₁₀ / MFR ₂ to R ₂ of 15 or less. 2. An intrinsic viscosity [η] measured in a decalin solvent at 135 ° C. is in a range of 1.5 to 3.5 dl / g,
Melting index MFR ₁₀ and 190 at 190 ° C under a load of 10 kg
Ratio MF to melting index MFR ₂ under a load of 2.16 kg
A polishing material containing polyethylene whose R ₁₀ / MFR ₂ is 15 or less as a main component. 3. A melt index MFR ₂ under a load of 2.16 kg at 190 ° C. of 0.05 to 3 g / 10 min, and a molecular weight distribution Mw / M determined by gel permeation chromatography.
A polishing material mainly composed of polyethylene having n of 8 or less. 4. An intrinsic viscosity [η] measured in a decalin solvent at 135 ° C. is in the range of 1.5 to 3.5 dl / g,
A polishing material mainly composed of polyethylene having a molecular weight distribution Mw / Mn of 8 or less as determined by gel permeation chromatography. 5. A polishing material according to claim 1, wherein the polishing material is a spherical, rugby ball, disk, elliptical or columnar shaped body.