JPH06195821A - Magnetic tape guide roller - Google Patents

Abstract

PURPOSE:To enhance the traveling reliability by fitting a roller for guiding a magnetic tape in its traveling to an outer circumference of a supporting pin to become the magnetic tape guide roller and constituting the roller out of resin components consisting of polyethylene resin and a prescribed amt. of silicone oil without a functional group. CONSTITUTION:The roller 2 in a cylindrical shape is freely rotatably or integrally fitted to the outer circumference of the supporting pin 1, and flanges 3 are provided on both end parts of this roller to make the guide roller. In such constitution, if the roller 2 is freely rotatably supported by the pin 1, the roller is rotated in accordance with the tape traveling, and if the roller 2 is integrally fixed to the pin 1, the tape is brought into slide contact with the outer circumference of this roller. In this constitution, the roller 2 is composed of the resin components consisting of polyethylene resin and 0.5-20wt.% of silicone oil without a functional group. Thus, no variation of a friction coefft. takes place even when a temp. is changed, and stabilization is acquired for a long time without making a void and a crack.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Generally, a video tape recorder (VT)
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 the running thereof, the one shown in FIG. 1 is generally used.

That is, this is one in which a cylindrical roller 2 is rotatably or integrally attached to the outer periphery of a support pin 1 and flanges 3 are attached to both ends thereof. Fluoroethylene resin (PTF
It is made of a self-lubricating synthetic resin such as a polyacetal resin containing a fluororesin such as E) or an oil-containing resin. If the roller 2 is rotatably supported by the support pin 1, the roller 2 rotates as the magnetic tape runs, and the roller 2 integrally fixed to the support pin 1 has a magnetic tape on the outer periphery thereof. The sliding contact is made to guide the traveling.

However, the polyacetal resin that constitutes the roller 2 has the drawback that it is difficult to use it with a sufficiently reduced friction coefficient and that the friction coefficient fluctuates due to environmental changes such as temperature changes. In addition, the oil-containing resin lacks the lubricating oil in the surface layer.

As a magnetic tape guide roller equipped with the roller 2 which has improved such a defect, the inventors of the present application have previously disclosed it in Japanese Patent Application Laid-Open No. 63-146261, such as polyethylene. There is one in which the roller 2 is formed of a resin composition obtained by blending the above-mentioned thermoplastic resin with an organopolysiloxane having a functional group.

[0006]

However, if a thermoplastic resin such as polyethylene is blended with an organopolysiloxane having a functional group, the thermoplastic resin may be molded by heating.
This resin reacts with functional groups, and voids and cracks are likely to occur in the molded roller, so it is difficult to obtain stable rotation torque for the magnetic tape guide roller and characteristics such as rotating for a long time with little shake. The problem arises.

Therefore, the present invention solves the above-mentioned problems, and the magnetic tape guide roller has a friction coefficient which does not fluctuate in response to environmental changes such as temperature changes, and has no voids or cracks in the roller. It is an object of the present invention to make the rotational torque and the runout as stable as possible for a long time, and to sufficiently improve the reliability of the running state of the magnetic tape.

[0008]

In order to solve the above-mentioned problems, in the present invention, a magnetic tape guide roller having 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. That is, the resin composition is composed of a resin and 0.5 to 20% by weight of a silicone oil having no functional group. The details will be described below.

First, the polyethylene resin used in the present invention may be any one of low density, medium density, high density and ultra high molecular weight, and may be linear. Such a polyethylene resin can adopt a molding method such as melt molding or compression molding applied to a thermoplastic resin.

Next, the silicone oil used in the present invention is a polymer of dimethylsiloxane or a methyl group of dimethylsiloxane or a part thereof is hydrogen, a phenyl group,
It may be a derivative substituted with one or more aliphatic or aromatic residues such as halogenated phenyl group, halogenated alkyl group and fluoroester group. And, such silicone oil is a compound having no functional group. Examples of the functional group as used herein include 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, and these chemically react during the heat molding of the polyethylene resin. It is an easy atomic group. The viscosity of the silicone oil is preferably 5-500000 cst.

The mixing ratio of the silicone oil to the polyethylene resin is 0.5 to 20% by weight.
This is because if the amount is less than 0.5% by weight, the sliding characteristics cannot be sufficiently improved, and if the amount is more than 20% by weight, the mechanical properties of the polyethylene resin as the base material are impaired. A particularly preferable blending ratio is 1 to 15% by weight.

As the method for mixing the resin composition in the present invention, a well-known method may be used.
For example, the polyethylene resin and the silicone oil, which are the base materials, may be individually or individually dissolved in a solvent (for example, fluorochlorohydrocarbon) and mixed with a mixer such as a Henschel mixer, a ball mill or a tumbler mixer, and then the solvent is added. It may be removed and supplied to an injection molding machine or a melt extrusion machine with good melt mixing properties, or it may be melt mixed in advance using a heat roller, kneader, Banbury mixer, melt extrusion machine, etc. A method of mixing and molding immediately before molding may be used.

In addition to the polyethylene resin and silicone oil, which are the main raw materials of the present invention, additives that are widely applicable to general synthetic resins may be used together to the extent that the object of the present invention is not impaired. Examples of such additives include mold release agents, flame retardants, weather resistance improvers, other tetrafluoroethylene resins, graphite, fluorinated graphite, talc, industrial lubricants such as boron nitride, glass fibers, carbon fibers. , Alumina fiber, asbestos, rock wool, wollastonite, reinforcing agents made of fibrous substances such as potassium titanate whiskers, glass powder, talc, clay, inorganic fillers represented by calcium carbonate, etc.,
The method of adding these is not particularly limited.
Further, it goes without saying that the form of the intermediate product or the final product can be modified to improve its properties by chemical or physical treatment as long as the lubricity of the resin composition of the present invention is not impaired.

[0014]

In the magnetic tape guide roller of the present invention, the affinity between the base material polyethylene and the silicone oil is very good, and the silicone oil is securely held in the polyethylene in extremely fine dispersion units. Does not have a functional group, so voids and cracks do not occur during molding. Therefore, the lubricity of the silicone oil is stably exhibited when the guide roller is rotated, the rotational torque is stabilized, the wear resistance is improved, and the roller runout does not occur. Further, since the guide roller is relatively soft, it does not damage the tape even in the sliding state.

[0015]

EXAMPLES The raw materials used in Examples and Comparative Examples are collectively shown below. In addition, the abbreviations are appropriately shown in [].

(1) Polyethylene Mitsui Petrochemical Co., Ltd .: Hi-Zex 1300J (2) Polyethylene Hoechst, Germany: Ultra high molecular weight polyethylene Hostalene GUR212 (3) 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 Daicel-Huls Manufactured by: Daiamide L1640P (8) Polyethylene terephthalate [PETP] Made by Akzo Plastics of the Netherlands: Arnite
A160 [Examples 1 and 2, Comparative Examples 1 to 7] Raw materials were blended in the blending ratio (wt%) shown in Table 1, and the results were shown in FIG. 1 under the melt-mixing conditions and injection molding conditions shown in the same table. A rotor 2 having the same shape as the rotor and having an outer diameter of 4 mm and an inner diameter of 2.5 mm was formed. Then, the rotating body 2 was assembled to the support pin made of SUS304 (surface roughness 0.2 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 FIG.

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 a guide roller for the sample was mounted on the measurement plate and measurement was performed. Pressure 20
A torque pickup measures a measurement plate that moves due to friction generated between the rotating body and the support pin when the rotating body of the guide roller is pressed against the side surface of the rotating disk with kgf and the number of rotations is 5000 rpm. Using such a guide roller torque measuring device, the number of revolutions of the rotating body was set to 5000 times per minute by belt tension, 40 ° C., and relative humidity 8
The elapsed time and the change in torque of the guide roller during continuous rotation under 0% 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 a 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.

[0020]

[Table 1]

[0021]

[Table 2]

Example 3 Ultrahigh molecular weight polyethylene powder and silicone oil were mixed in a blending ratio shown in Table 1 using a Henschel mixer, and then the temperature was 190 ° C. and the pressure was 4
Hot-homing compression molding was performed under the condition of 50 kgf / cm ² to obtain a molded product having an outer diameter of 20 mm and a length of 50 mm. This formed body was cut to form a guide roller having the same shape as that of Example 1.

About the obtained guide roller, Example 1
Tests and tests were conducted in the same manner as above, 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 Table 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 3, the rotational torque was stable and low during the test time of 500 hours, and no tendency to increase was found.

As for the runout of the rotating body, in Runs 1, 3, 4, 6 and 7, the runout increased to 5 μm or more by the lapse of 200 hours, and especially in Runs 3 and 7.
Exceeds 10 μm. In Comparative Example 5, the runout is smaller than the others, but the rotation torque is large as described above. In addition,
When the inside of the guide roller of Comparative Example 5 was examined, a large amount of abrasion powder was generated, clogging the inner diameter hole and adhering to the support pin. 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 3 hardly changed with time, and no generation of abrasion powder was found inside.

Therefore, it can be expected that the VTR and DAT equipped with the magnetic tape guide rollers of Examples 1 to 3 will improve image shake, jitter, and wow as much as the vibration width of the magnetic tape is small.

[0027]

As described above, according to the present invention, the roller in the magnetic tape guide roller is made of polyethylene resin.
Formed with a resin composition consisting of a certain amount of silicone oil that does not have a functional group, the silicone oil is securely retained in the polyethylene in extremely fine dispersion units, and friction against environmental changes such as temperature changes The coefficient does not fluctuate, and since the silicone oil does not have a functional group, voids and cracks do not occur during the molding process, so the rotational torque and runout are stable and small for a long time, and the magnetic tape There is an advantage that the reliability of the running state can be sufficiently enhanced.

[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 graph showing changes over time in the rotational torque of the example or comparative example.

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

[Explanation of symbols]

 1 Support pin 2 Rotating body 3 Flange

Claims (1)

[Claims] 1. 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 comprises polyethylene resin and 0.5 to 20% by weight of a functional group-free silicone oil. A magnetic tape guide roller formed of a resin composition comprising