JPH08269255A - Lubricating resin composition - Google Patents

Abstract

PURPOSE: To obtain a lubricating resin compsn. which can be extruded efficiently and gives a magnetic-tape guide roller which has lubricating characteristics basically required and can be produced efficiently. CONSTITUTION: A lubricating resin compsn. usable for a magnetic-tape guide roller is obtd. by compounding a polyethylene resin with 0.1-20wt.% alkyl- modified silicone oil. In a magnetic-tape guide roller wherein a roller 2 for guiding the travelling of a magnetic tape is installed around a support pin 1, the roller 2 installed is produced from a resin compsn. comprising a polyethylene resin and 0.1-20wt.% alkyl-modified silicone oil.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lubricating resin composition and a magnetic tape guide roller mounted on a magnetic recording device using the same.

[0002]

2. Description of the Related Art Generally, a video tape recorder (VT)
1) is known as a typical example of a magnetic tape guide roller that winds a magnetic tape such as R) or a digital audio tape recorder (DAT) and guides its running.

That is, in the illustrated magnetic tape guide roller, a cylindrical roller 2 is rotatably or integrally mounted on the outer periphery of a support pin 1 and flanges 3 are attached to both ends thereof. Is formed of a self-lubricating synthetic resin such as a polyacetal resin containing a fluororesin such as polytetrafluoroethylene resin (PTFE), or an oil-containing resin. The roller 2 is rotatably supported by the support pin 1 and rotates with the running of the magnetic tape, and the roller 2 is integrally fixed to the support pin 1 so that the magnetic tape is slidably contacted with the outer periphery of the roller 2. There is a method of guiding.

A guide that the polyacetal resin as the material for forming the roller 2 is difficult to sufficiently reduce the friction coefficient, and the friction coefficient varies due to environmental changes such as temperature change. It has physical properties unfavorable as a roller. Further, the roller made of an oil-containing resin has a drawback that the lubricating oil in its surface layer portion is insufficient.

The inventor of the present application has previously disclosed Japanese Patent Laid-Open No. 63-14.
The magnetic tape guide roller disclosed in Japanese Patent No. 6261 is mainly composed of a thermoplastic resin such as polyethylene,
The resin composition comprises an organopolysiloxane having a functional group.

[0006]

However, when a thermoplastic resin such as polyethylene is blended with an organopolysiloxane having a functional group and the mixture is heat-molded, the resin reacts with the functional group and the roller of the molded product is reacted. Voids and cracks are likely to occur in the magnetic tape guide roller. Therefore, the magnetic tape guide roller could not be rotated in a state where stable rotational torque and long-term shake were small.

With respect to such a problem, the magnetic tape guide roller disclosed by the inventors of the present application in Japanese Patent Application Laid-Open No. 6-195821 has a polyethylene-reactive functional group such as an amino group and an epoxy group. Group, alcoholic hydroxyl group,
The lubricating resin composition comprises a silicone oil having no mercapto group or carboxyl group.

[0008] This product has a small rotational torque and runout in a mounted state and is stable, and is excellent in the original function of the guide roller.

However, this product has a problem that polyethylene and silicone oil are separated during the molding process and adhere to the surface of the screw of the extruder, thereby lowering the molding efficiency. Further, when a magnetic tape guide roller made of such a resin composition is used under a temperature condition exceeding room temperature, silicone oil may exude from the resin composition and contaminate the tape slidingly contacted with the silicone oil in some cases. appear.

Therefore, the present invention solves the above-mentioned problems and provides a lubricating resin composition which has a low friction characteristic and a sliding characteristic excellent in wear resistance, and which is effective in extruding without lowering the molding speed. In addition, the magnetic tape guide roller can be molded well, the rotation torque and runout in the mounted state are small, and the performance is stable, and the lubricating oil does not exude excessively even at high temperatures, and the production efficiency is improved. The challenge is to make it expensive.

[0011]

In order to solve the above problems, in the present invention, a polyethylene resin is blended with 0.1 to 20% by weight of an alkyl-modified silicone oil to provide a lubricating resin composition. is there.

Alternatively, a lubricating resin composition for a magnetic tape guide roller is obtained by blending 0.1-20% by weight of an alkyl-modified silicone oil with a polyethylene resin.

Furthermore, in a magnetic tape guide roller in which a roller for guiding the running of the magnetic tape is attached to the outer periphery of the support pin, the roller is a polyethylene resin and an alkyl-modified silicone oil is added in an amount of 0.1 to 20% by weight. It was formed from the lubricating resin composition.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION First, the polyethylene resin in the present invention comprises a main chain containing —CH ₂ —CH ₂ —
Depending on the degree of crystallization, low density, linear low density, medium density, high density, ultra high molecular weight ones can be adopted, and linear ones or branched ones containing CH ₃ branches May be CH _{3 in} this case is, for example, about 1 to 50.
%, About 3 to 10% or about 10 to 30% (wt% or mol%) may be blended, and the optimum blending ratio can be selected. Such a polyethylene resin can adopt a molding method such as melt molding or compression molding applied to a thermoplastic resin.

Specifically, low-density polyethylene has about 2
It is manufactured at high temperature and high pressure of about 3,000 to 3,000 atm and about 150 to 300 ° C, has a specific gravity of about 0.91 to 0.925, which is smaller than that of other polyethylene, and has a crystallinity of about 45 to 55% and a melting point of about 100 to 120 ° C. It is also called high-pressure polyethylene or soft polyethylene. Medium / high density polyethylene is manufactured at a low temperature and low pressure of 0 to 100 atm and about 50 to 200 ° C, a specific gravity of about 0.926 to 0.94, a crystallinity of about 50 to 60%, and a melting point of about 120 to 125 ° C. And then
It is also called low-pressure polyethylene, hard polyethylene, or linear low-density polyethylene. The one having a specific weight of 0.926 to 0.94 is also referred to as medium density polyethylene. In addition, it is about 1 in high density polyethylene.
Some are manufactured at medium to low temperatures and medium pressures of 0 to 60 atm and about 100 to 170 ° C. Specific gravity is about 0.941 to 0.97, crystallinity is about 65 to 85%, and melting point is about 65 to 85 ° C. Things are
Also called medium pressure polyethylene or rigid polyethylene.

High-pressure polyethylene has long linear molecules with many branches and is resistant to heat and ultraviolet rays. Medium- and low-pressure polyethylene has a slight amount of branching, double bonds, good molecular orientation, and is moderately hard, and it has the following properties: moldability during molding, moldability, and wear resistance. Etc. are excellent. High-pressure polyethylene has a viscosity average molecular weight of about 1
It can be about 500,000, about 1 to 150,000, or about 100,000 to 400,000.

On the other hand, the viscosity average molecular weight of ultra high molecular weight polyethylene can be about 50 to 8,000,000, about 1 to 6,000,000 or about 1 to 4,000,000, but the intrinsic viscosity by the solution viscosity method is about 8 to 40 dl. / g, the viscosity average molecular weight is about 1 to 8 × 10 ⁶ , and the density is about 0.92 to
The crystallinity is 0.94, which is about the same as the above.

As described above, due to high density and high molecular weight, wear resistance, self-lubrication, impact resistance, chemical resistance, lightness less than specific gravity of water, dimensional stability due to low water absorption, etc. Excellent in various characteristics.

Examples of the polyethylene-based resin include low molecular weight polyethylene, modified polyethylene which is a graft copolymer, chlorinated polyethylene, crosslinked polyethylene, foamed polyethylene and the like, in addition to the above-mentioned resins. Further, the above-mentioned polyethylene-based resin may be used alone or in combination of two or more kinds of polyethylene, for example, about 1 to 80 parts by weight, preferably about 5 to 50 parts by weight, relative to about 100 parts by weight of the main component polyethylene. Preferably, about 25 to 60 parts by weight may be blended.

Among these polyethylene resins,
The crystallinity is 50 to 90% or more, and the specific gravity or density is about 0.
926 to 0.97 or more (ASTM D792), durometer or Shore hardness of about D50 to 72 or more (AST
M2240), or about R35 in Rockwell hardness
~ 45 (ASTM D785) melting point about 120-140
℃ or more (ASTM D2117) Vicat softening point is about 9
0 to 135 ° C or higher (ASTM D1525), heat distortion temperature of about 49 to 88 ° C or higher (ASTM D648, 4.6)
(kg / cm ² ) Water absorption is about 0.015% or less, preferably about 0.01% or less (ASTM D570, thickness 3 m
m, 24 hours) is preferable. In addition,
The values in parentheses () are the preferred measurement methods, but the test conditions are not particularly limited.

If the crystal temperature, the specific gravity, the density or the hardness is too low, the rotor may be deformed by the load applied to the roller portion of the magnetic tape. It causes the life. If the melting point, the Vicat softening point and the heat deformation temperature are too low, the heat deformation of the rotor is expected due to the frictional heat caused by the rotary sliding of the rotor and the support pin, and if it is too high, the moldability becomes difficult.

Further, the lower the water absorption, the less the generation of cavities (porous portion) during molding, and the long-term dimensional stability of the rotor can be expected. Further, for example, the melt viscosity is 0.01 at the melt index value (melt flow rate).
˜20 g / 10 min (ASTM D1238), and about 0.1 to 1.5 g / 10 min in melt extrusion, it is efficient and continuously excellent in physical properties, and also has compatibility and dispersibility with silicone-based oil described below. An excellent molded product can be manufactured. If the above value is too small, molding becomes difficult,
If it is too large, the heat resistance and wear resistance will decrease.

Of the various molding methods, compression molding is suitable for ultrahigh molecular weight polyethylene resins having relatively low fluidity. The extrusion molding is suitable for medium / high-density polyethylene-based resin having a slightly good fluidity, and can provide a rotating body which is superior in production efficiency to compression molding and has excellent physical properties. Injection molding is suitable for polyethylene resin having a relatively low molecular weight and good fluidity, and is superior in production efficiency to extrusion molding.

The extrusion molding method, preferably the melt extrusion molding method, can efficiently produce an excellent polyethylene resin molding. For example, the cylinder temperature is about 150-20
0 ° C., the mold temperature is about 120 to 170 ° C. on the extruder side, about 70 to 120 ° C. on the tip side of the molded product outlet, and the screw rotation speed is about 5 to 30 rpm, preferably about 5 to 15 rpm.
Is good. Because, if the cylinder temperature is too low, the resin will not dissolve sufficiently, and if it is too high, the decomposition of the resin will proceed,
Further, it is not preferable because the resin material is subjected to severe heat history. Also, if the mold temperature is too low, the molten resin is rapidly cooled and the shrinkage of the molded body becomes uneven, resulting in sink marks,
If it is too high and causes a warp, etc., the resin becomes hard to solidify and is not efficient. If the rotation speed of the extrusion screw is too slow, the productivity will be poor, and if it is too fast, the screw will slip and it will be difficult to form it into a predetermined shape, which may cause cavities.

Next, the alkyl-modified silicone oil used in the present invention comprises a polymer such as dimethylsiloxane, methylphenylsiloxane or methylhydrogensiloxane, and has a methyl group or a phenyl group at the side chain portion of the siloxane or at the polymer terminal portion. , A part of hydrogen is substituted with an alkyl group having 2 or more carbon atoms (—C _n H _{2n + 1} ). Such silicone oil can be produced by addition-reacting an α-olefin with a polysiloxane having a Si—H group under a platinum catalyst, and has a structure having Si—O—Si as a main chain. Is.

Such an alkyl-modified silicone oil has an aliphatic or aromatic group such as a halogenated phenyl group, a halogenated alkyl group or a fluoroester group, in addition to the portion substituted with an alkyl group. It may be a derivative substituted with a residue or a functional group such as an epoxy group, an amino group, a carboxyl group, a hydroxyl group, a mercapto group, an isocyanate group, a cyanate group and a vinyl group. The viscosity of the silicone oil is 5 to 50.
0000 cst is preferable.

Specifically, the alkyl-modified silicone oil may have an average molecular weight of at least about 300 or more, and is preferably 1000 or more, preferably 2000 or more, since it has an appropriate viscosity. For these reasons, those of 3000 or more are particularly preferable. Regarding the lower limit of the viscosity of such an oil, the viscosity at 100 ° C. is preferably about 2 cSt or more, more preferably about 10 cSt or more, further preferably 20 cSt or more or 30 cSt or more, or the viscosity. The index is preferably about 20 or more, more preferably about 100 or more, and further preferably about 200 or more or 30.
It is 0 or more. The alkyl-modified silicone oil may have one or more of such characteristics.

When such silicone oil and polyethylene are melt-mixed, it is preferable that the viscosity of the silicone oil and polyethylene are as close as possible because the compatibility and dispersibility are improved.

As described above, when the alkyl-modified silicone oil has an appropriate viscosity when heated, the sliding portion of the rotating body such as a roller is brought into contact with the support shaft to, for example, about 60 ° C.
Even if a frictional heat exceeding 10 is generated, the viscosity of the lubricating oil does not decrease and the oil does not exude suddenly from the rotating body, and the oil is appropriately held in the rotating body.

The upper limit of the viscosity of this oil is not particularly limited, but in order to make the oil dispersion uniform during granulation for molding pellets, extrusion molding, injection molding, etc. Molecular weight less than about 50,000, preferably 1
0000 or less, and 1000 at a viscosity of 40 ° C.
0 cSt or less, preferably 1000 cSt or less, 100
Viscosity at 5,000 Cst or less, preferably 500 cSt
It may be St or less. The viscosity index may be 1000 or less, preferably 500 or less.

Such a lubricating oil is mixed with an appropriate viscosity even when the temperature becomes high during pellet granulation, extrusion molding, injection molding, etc., and a uniform molded body is obtained without causing dispersion failure. Tissue can be obtained. On the other hand, a silicone-based oil / grease which does not exceed the melt viscosity of polyethylene when melt-mixed with polyethylene may be used, but it is preferable that it is not in the form of silicone resin or silicone rubber.

The n of the alkyl group is about 1 to 10 or 1 to 4, and each may be in the state of methyl group, ethyl group, propyl group, butyl group, etc. The blending ratio is about 1 to 50%, preferably about 3
The content is about 10%, more preferably about 10 to 30%. In this case,% may be either weight% or mol%.

Here, if the alkyl group n is too small,
The viscosity of a given silicone oil is too low, and it easily exudes from the rotating body.
The dispersibility may be reduced.

Examples of commercially available alkyl-modified silicone oils as described above include Shin-Etsu Chemical Co., Ltd .: Silicone oil KF-412, 413, 414 and Toray Dow Corning Silicone: SH203.

The compounding ratio of the alkyl-modified silicone oil to the polyethylene resin is 0.1 to 20% by weight. This is because if the amount is less than 0.1% by weight, the sliding characteristics cannot be sufficiently improved, and if the amount is more than 20% by weight, the formability is significantly impaired. From such a tendency, a particularly preferable mixing ratio is 0.3 to 10.
% By weight. It is also possible to add the alkyl-modified silicone oil and other silicone oil in combination.

The method of mixing the resin composition in the present invention may be a well-known method, for example, the polyethylene resin and the silicone oil, which are base materials, individually or in a solvent (for example, fluorocarbon). Chlorohydrocarbon etc.)
After mixing with a mixer such as a Henschel mixer, ball mill, tumbler mixer, etc., remove the solvent and supply it to an injection molding machine or a melt extrusion machine with good melt mixing properties, or in advance a heat roller, kneader, Banbury mixer, melt extrusion It may be melt-mixed using a machine or the like, or may be a method in which granulated pellets are mixed and molded immediately before molding. Also, medium / high-density polyethylene and ultra-high-molecular-weight polyethylene can be granulated once to form pellets, and then melt-extruded to efficiently obtain a molded product with good physical properties.

In addition to the polyethylene resin and the alkyl-modified silicone oil, which are the main raw materials of the present invention, additives that can be widely applied to general synthetic resins may be used together in an amount that does not impair the object of the present invention. .

Examples of such additives include mold release agents, flame retardants, weather resistance improvers, industrial lubricants such as tetrafluoroethylene resin, graphite, fluorinated graphite, talc and boron nitride, and glass fibers. , Carbon fiber, alumina fiber, asbestos, rock wool, wollastonite, reinforcing agents made of fibrous substances such as potassium titanate whiskers, inorganic fillers such as glass powder, talc, clay, calcium carbonate, etc. The method of adding these is not particularly limited.

Further, it is needless to say that the intermediate product or the final product form can be modified for the purpose of improving the properties by a separate chemical or physical treatment as long as the lubricity of the resin composition of the present invention is not impaired. Is.

The surface shape and surface roughness of at least the sliding surface of the rotating body, the support pin, and the magnetic tape are the maximum roughness (Rm
ax), arithmetic mean roughness (Ra), ten-point mean roughness (Rz)
It is about 0.1 to 8 μm, preferably about 0.1 to 5 μm. If the surface roughness / shape is smaller than the predetermined range, the machining such as cutting becomes inefficient, and if it is too large, it causes uneven rotation and wear of each member. In addition, in order to reduce rotational runout, the surface roughness
In addition to the shape, the circularity, cylindricity, and concentricity of at least one of the outer diameter and inner diameter of the rotating body and the support shaft is about 0.1 to 10μ
m, preferably about 0.1 to 6 μm, is subjected to precision cutting to obtain a guide roller assembly with higher accuracy.

[0041]

In the resin composition of the present invention, the affinity between polyethylene and alkyl-modified silicone oil is very good, so that the alkyl-modified silicone oil is reliably retained in the polyethylene in a fine dispersion unit.

Therefore, the sliding characteristics of the silicone oil can be stably exhibited on the sliding surface of the resin composition, and the excellent friction and abrasion characteristics are exhibited. For the same reason, the resin and the oil are not separated during the extrusion molding process, so that stable and good moldability is exhibited.

In the magnetic tape guide roller of the present invention, due to the physical properties of the above-mentioned lubricating resin composition, the rotational torque is stable, the wear resistance is improved, and roller runout does not occur, and the performance is high. As described above, the production efficiency is high with stable and good moldability.

The polyethylene resin has a specific gravity of about 1
Since it is a lightweight material of g / cm ³ or less, it has little influence of inertia as a rotating body such as a guide roller used at high speed rotation, and can relatively well cope with sudden acceleration and sudden stop of a magnetic tape.

[0045]

EXAMPLES The raw materials used in Examples and Comparative Examples are collectively shown below. The abbreviations are shown in [].

(1) Polyethylene: Mitsui Petrochemical Co., Ltd .: Hi-Zex 8200B (2) Alkyl-modified silicone oil: Shin-Etsu Chemical Co., Ltd .: KF412 (3) Silicone oil (unmodified dimethyl silicone oil): Shin-Etsu Chemical Co., Ltd .: KF96H-6000 (4) Polyacetal Polyplastics: Duracon M90 (5) Powdered tetrafluoroethylene resin [PTFE powder] Kitamura: KT400M (6) Synthetic oil Nippon Oil & Fats: Ester oil Unistar H (7) ) Nylon 12 Made by Daicel-Huls: Daiamide L1640P (8) Polyethylene terephthalate [PETP] Netherlands Made by Akzo Plastics: Arnite
A160.

[Examples 1 to 4 and Comparative Examples 2 and 8] Raw materials were blended in a blending ratio (% by weight) shown in Table 1 or Table 2 and kneaded under the melt mixing conditions shown in the same table, and the screw outer diameter was 32 mm. Cylinder temperature of 17 using a single screw extruder
Outer diameter 5m under conditions of 0 ° C, mold temperature: 140 ° C (extruder), 90 ° C (tip side), screw rotation speed 10 rpm
m bar material was formed.

This rod is cut to form a rotor 2 having the same shape as the rotor shown in FIG. 1 and having an outer diameter of 4 mm and an inner diameter of 1.5 mm. The rotor 2 is made of a SUS304 support pin (having a surface roughness of 0. Two
μm). The gap between the support pin 1 and the rotating body 2 at that time was about 5 μm.

The rotation torque and runout of the guide roller were measured by the following test method, and the results are shown in Table 2 and further shown in the graph of FIG. 2 or 3.

Rotational Torque Test Method A measurement plate supported by a hydrostatic air bearing was provided on the concentric core of a rotating disk (diameter 100 mm, thickness 6 mm), and the guide roller of the example or comparative example was provided on this measurement plate. The rotating body of the guide roller is attached to the side surface of the rotating disk at a pressure of 20 kgf to set the rotation speed to 5000 times per minute, and the measuring plate that moves due to the friction generated between the rotating body and the support pin at this time is torqued. Measure with a pickup. Using a guide roller torque measuring device equipped with such a mechanism, the number of rotations of the rotating body was set to 5 per minute by belt tension.
It was set to 000 times, and the elapsed time and the change in torque of the guide roller when continuously rotated at 40 ° C. and 80% relative humidity were examined.

Deflection Test Method A support pin of a sample guide roller is fixed, a dial gauge (1/1000) is pressed against the center of the rotating body, and the rotating body is gently rotated. At this time, the difference between the maximum value and the minimum value of the dial gauge value was obtained, and this was used as the shake. The belt tension is set to 5000 rpm and 40
The elapsed time and the change in deflection of the guide roller during continuous rotation under conditions of ° C and a relative temperature of 80% were examined.

Extrusion Moldability The relationship between the extrusion speed and the elapsed time in the case where the above single-screw extruder was used under the same conditions and extrusion molding was continuously performed for 12 hours is shown in the chart of FIG.

[0053]

[Table 1]

[0054]

[Table 2]

[0055]

[Table 3]

[Comparative Examples 1 and 3 to 7] Raw materials were blended at the blending ratio (wt%) shown in Table 2, and the rotary body shown in FIG. 1 was obtained under the melt mixing conditions and injection molding conditions shown in the same table. A rotor 2 having the same shape and an outer diameter of 4 mm and an inner diameter of 1.5 mm was formed, and a guide roller having the same shape as that of Example 1 was prepared. Incidentally, if the dimensional accuracy cannot be obtained only by injection molding, cutting processing was performed.

Using the obtained guide roller as a test object,
Tests and tests were conducted in the same manner as in Example 1, and the obtained results are shown in Table 2 and further shown in FIG. 2 or 3.

As is clear from the test results of Tables 1 and 2 and the graph of FIG. 2 or FIG. 3, in Comparative Examples 4, 5 and 7 in which the base material was other than polyethylene, the rotational torque increased with time.

On the other hand, in Examples 1 to 4 and Comparative Example 2,
The rotation torque during the test time (500 hours) was stable and low, and no tendency of the torque value to rise was found.

In Comparative Example 8, the resin material could not be molded into the screw of the extruder because the resin material was not sufficiently penetrated (cut into the screw).

Further, regarding the diametrical deflection of the rotating body, in Comparative Examples 1, 3, 4, 6 and 7, the deflection increased to 5 μm or more by the lapse of 200 hours, and particularly in Comparative Examples 3 and 7. It exceeded 10 μm. In Comparative Example 5, the runout is smaller than the others, but the rotation torque is large as described above. The inside of the guide roller of Comparative Example 5 was examined.
A large amount of wear debris was generated, clogging the inner diameter hole and adhering to the support pins. Therefore, in Comparative Example 5, it was speculated that the wear progressed uniformly or the runout decreased by chance due to the presence of wear powder.

On the other hand, the shakes of Examples 1 to 4 and Comparative Example 2 hardly changed with time, and no generation of abrasion powder was found inside.

Further, regarding the extrusion moldability of the resin composition from the results of FIG. 4, in Comparative Example 2 in which unmodified silicone oil was blended, the extrusion rate decreased as the molding time passed. This phenomenon is due to slippage between the screw of the extruder and the resin material, and when the extruder was disassembled after molding, silicone oil adhered to the screw.

On the other hand, in Examples 1 to 4 in which a predetermined amount of the alkyl-modified silicone oil was blended, the initial extrusion rate could be maintained 12 hours after the start of molding, and excellent moldability was exhibited.

Therefore, in the VTR and DAT equipped with the magnetic tape guide rollers of Examples 1 to 4, wow such as image shake, jitter, wow and flutter is improved by the amount of the vibration width of the magnetic tape being small. Can be expected.

[0066]

As described above, the present invention has the advantage that it can be efficiently molded at the time of extrusion molding because it is a lubricating resin composition in which a predetermined amount of an alkyl-modified silicone oil is mixed with a polyethylene resin.

Further, since the roller in the magnetic tape guide roller is formed of a resin composition composed of polyethylene resin and alkyl modified, the rotational torque and the runout in the mounted state are small and stable, and the temperature is high in the used state. Even if it becomes, the silicone oil is difficult to seep out and has high performance. In addition, this is also advantageous in that the resin composition is stable and has good moldability, and the production efficiency is high.

[Brief description of drawings]

FIG. 1 is a partially cutaway side view illustrating a structure of a magnetic tape guide roller.

FIG. 2 is a chart showing a change with time of a rotation torque of an example or a comparative example.

FIG. 3 is a chart showing changes over time in the shake of Examples or Comparative Examples.

FIG. 4 is a chart showing a change with time of an extrusion speed during molding of Examples or Comparative Examples.

[Explanation of symbols]

 1 Support pin 2 Rotating body 3 Flange

Claims (3)

[Claims] 1. A lubricating resin composition comprising a polyethylene resin and 0.1 to 20% by weight of an alkyl-modified silicone oil. 2. A lubricating resin composition for a magnetic tape guide roller, which comprises a polyethylene resin and 0.1 to 20% by weight of an alkyl-modified silicone oil. 3. A magnetic tape guide roller in which a roller for guiding the running of a magnetic tape is attached to the outer periphery of a support pin, wherein the roller is made of polyethylene resin and 0.1-20% by weight of alkyl-modified silicone oil is compounded. A magnetic tape guide roller formed of a lubricating resin composition.