JP2538601B2 - Post base - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is for fixing and holding posts such as a rotating post and an inclined post in a recording, recording and reproducing device using a magnetic tape such as audio and video. Post base,
More specifically, it relates to a post base composed of a resin molded product mainly composed of polyarylene sulfide.

[Conventional technology and its problems]

A recording / reproducing apparatus using a magnetic tape for audio, video, etc. has a rotating post, an inclined post, a vertical post, a fixed post, a limiter for the purpose of guiding the running of the magnetic tape or changing the running direction of the tape. Posts called posts, tension posts, etc. are provided, and these posts are fixed and held by a part called a post base to perform their functions.

Here, one embodiment of a post base in which posts are incorporated is as shown in FIG. 1, in which 1 is a post base and 2 and 3 are posts. The shape and configuration of the post base and posts are not limited to those shown in FIG. 1, but generally differ depending on the individual model and the intended function and intended use. A rod-shaped object provided for guiding the traveling of the tape or changing the traveling direction, and one having a roller attached thereto are referred to as posts here, and a component for fixing and holding this is referred to as a post base. . This includes the capstan base.

Such post bases are required to have a high degree of dimensional accuracy, dimensional stability, strength, rigidity, etc. in order to allow the tape to run stably via posts fixed to the post base. Most of them were made by die casting. However, the post base made of metal is complicated not only in the material cost, but also in the processing steps for forming a complicated shape, the surface treatment for improving the surface property, and the post-processing for attaching the posts. However, there is a problem in that the manufacturing unit price increases.

On the other hand, in view of such a problem of the metal post base, in recent years, there has been an attempt to reduce the cost by making it a resin. However, the post base has
As mentioned above, extremely high performance is required, and it is also required that the posts are excellent in press-fitting characteristics for press-fitting or tapping and mounting, and tapping property, self-tapping property, etc. Nothing has been found that can meet such demands. In addition, static electricity generated when the tape comes into contact with posts and travels interferes with the tape's running properties and adversely affects sound quality and image quality.
It is desirable for the post base to have appropriate conductivity or antistatic properties, but in order to achieve such an object, substances such as carbon black compounded in the resin often reduce the thermal stability of the resin, and the post base Making it more difficult to make into resin.

[Means for solving problems]

The present inventor has solved the above-mentioned problems associated with the resinization of the post base, stably exerted excellent performance, and as a result of earnest study to obtain an inexpensive post base, the specific characteristics of the post base material were obtained. By using a polyarylene sulfide resin having, it was found that these problems can be solved at once, and the present invention has been achieved.

That is, the present invention is a post base for fixing posts for guiding tape running of a recording / reproducing apparatus using a magnetic tape, wherein the base is a resin mainly composed of polyarylene sulfide, and a carbon-based conductive material is mixed therein. 1 x 10
^The present invention relates to a post base comprising a resin molded product having a surface electrical resistivity of ¹ to 1 × 10 ¹⁰ Ω.

The polyarylene sulfide resin used as the base resin in the present invention has a structural formula of Ar-S (provided that Ar
Is a polymer having 90 mol% or more of repeating units represented by an aryl group), and its representative substance is Is a polyphenylene sulfide having 90 mol% or more of the following repeating units.

Among them, those having a melt viscosity of 10 to 20000 poises, particularly 100 to 5000 poises, measured under the conditions of a temperature of 310 ° C. and a shear rate of 1200 sec ⁻¹ are suitable.

In the present invention, such a polyarylene sulfide resin is used as a substrate, and a carbon-based conductive material is added to the substrate, and the surface electrical resistivity measured according to ASTM D-257 is 1 × 10 ¹ to 1 × 10 5. ^{A 10} Ω one is used.

Originally, the post contacts and slides with the tape as the magnetic tape travels, and the sliding produces static electricity that causes electrostatic charge. If this static electricity remains (charges), it will be attracted or repelled between the post and the tape. Due to the phenomenon, the running stability of the tape is significantly impaired, and the posts and the tape adsorb suspended matter such as dust, which causes noise during reproduction and causes a problem in the image. Therefore, it is necessary to quickly remove the charged static electricity in order to eliminate the obstacles due to such static electricity. Such static electricity is partially released into the air but is not sufficient, especially when the humidity is low. This alone is extremely insufficient.

Therefore, in order to remove such static electricity, it is necessary to electrically remove the static electricity to the substrate or the like through the post base that holds the post, and therefore the conductivity of the post base is important.
That is, the removal of static electricity from the post base depends on the conductivity of the post base material, in other words, the electric resistance value, and is specifically defined by the surface electric resistivity of the post base material. That is, the smaller the surface electrical resistivity, the better the conduction removal of the charged static electricity, and the above problem due to static electricity becomes more advantageous. However, according to the study by the present inventors, this value is set to 1 ×.
It was confirmed that when the resistance is 10 ¹⁰ Ω or less, the tape running stability due to the accumulation (charging) of the static electricity, the noise, and the troubles on the image are improved to an acceptable level. Further, it is more preferable that the surface electrical resistivity is 1 × 10 ⁵ Ω or less. The surface electrical resistivity of such a post base is a value that is not possible with a general synthetic resin containing polyarylene sulfide as it is, and it is essential to mix a conductive agent, and a carbon-based conductive agent, particularly carbon fiber or conductive carbon. Black blending is preferred, and as the blending amount of these conductive agents increases,
Since the surface electric resistivity decreases, the surface electric resistivity can be made 1 × 10 ¹⁰ Ω or less depending on the blending amount.

On the other hand, when the blending amount of the conductive agent increases, the surface electrical resistivity further decreases, but when the blending amount of the carbon-based conductive substance as described above becomes a certain limit or more, the composition at the time of melt kneading with polyarylene sulfide Of the polyarylene sulfide resin is impaired in the original processability of the polyarylene sulfide resin, and the carbon-based conductive material is chemically impaired. Since it is also active, it accelerates the decomposition and deterioration of the polyarylene sulfide resin, which has a high melting point and a relatively high molding and processing temperature, and the tensile strength / elongation, rigidity (bending property), and toughness inherent in the polyarylene sulfide resin It reduces mechanical properties such as impact resistance and, for example, the press-fitting properties, tap workability, self-tapping properties and durability required for post bases are impaired, which is preferable. No. Therefore, the smaller the surface electrical resistivity itself, the more preferable, but because of the above-mentioned reasons such as moldability, thermal properties, and mechanical properties, there is an upper limit in the amount of the carbon-based conductive agent blended, so polyarylene sulfide is present. It is extremely difficult to maintain the surface electrical resistivity of the molded product below 1 × 10 ¹ Ω. Even if the surface electric resistivity is not less than 1 × 10 ¹ Ω, the static electricity is sufficiently removed and the above-mentioned troubles due to the static electricity do not occur, so that the object of the present invention is achieved.

That is, the upper limit of the surface electrical resistivity of the post base of the present invention needs to be specified to be 1 × 10 ¹ Ω or less from the viewpoint of the effect of removing static electricity, and on the other hand, with the increase of the blending amount of the carbon-based conductive substance 1 × 10 ¹ Ω from the viewpoint of molding processability, stability, mechanical properties, etc. of polyarylene sulfide resin composition
It is difficult to control the surface resistance to be less than 1 and the surface electrical resistivity is in the range of 1 × 10 ¹ to 1 × 10 ¹⁰ Ω, preferably 1 × 10 ¹ to 1 ×, in the range where the objective effect of the post base of the present invention is comprehensively satisfied. 10 ⁵ Ω
It becomes the range of.

The amount of the carbon-based conductive agent blended depends on the type of substance used,
Generally 0.5-40% by weight of the total composition, depending on the nature
And preferably 1 to 30% by weight. Particularly, in the case of carbon fiber, 8 to 40% by weight, preferably 10 to 30% by weight, and in the case of conductive carbon black, 1 to 10% by weight, preferably 2 to 8% by weight, are preferable ranges. If both are too small, the surface electrical resistivity becomes large, causing tape runnability, noise, and hindrance to the image.If too large, the molding processability deteriorates and mechanical properties become insufficient. Not preferable.

In the present invention, the above-mentioned polyarylene sulfide used for the post base may be used in combination with other thermoplastic resin as a resin depending on the purpose.

The other thermoplastic resin used here may be any thermoplastic resin that is stable at high temperatures. For example, aromatic polyester such as polyethylene terephthalate and polybutylene terephthalate, and aromatic polyester composed of diol or oxycarboxylic acid, polyacetal (homo or copolymer), polystyrene, polyvinyl chloride, polyamide, polycarbonate, ABS, polyphenylene oxide, poly Examples thereof include alkyl acrylate and fluororesin. These thermoplastic resins can be used as a mixture of two or more kinds.

In the present invention, the polyarylene sulfide resin used for the post base has mechanical strength, heat resistance,
Depending on the purpose such as improvement in dimensional stability, a fibrous, powdery or plate-like filler may be blended.

As the fibrous filler, glass fiber, asbestos fiber, silica fiber, silica-alumina fiber, alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride fiber, boron fiber, potassium titanate fiber, stainless steel, aluminum, titanium Inorganic fibrous substances such as fibrous substances of metals such as copper, copper and brass. A particularly representative fibrous filler is glass fiber. In addition, polyamide, fluororesin,
High melting point organic fibrous substances such as polyester resin and acrylic resin can also be used.

On the other hand, as the granular filler, silica, quartz powder, glass beads, glass powder, calcium silicate, aluminum silicate, kaolin, talc, clay, diatomaceous earth, silicates such as wollastonite, iron oxide, and oxidation. Oxides of metals such as titanium, zinc oxide and alumina, carbonates of metals such as calcium carbonate and magnesium carbonate, sulfates of metals such as calcium sulfate and barium sulfate, other silicon carbide, silicon nitride, boron nitride, various metal powders Etc.

Examples of the plate-like filler include mica, glass flakes, various metal foils and the like.

These inorganic fillers can be used alone or in combination of two or more. Especially when the carbon-based conductive material is conductive carbon black, a fibrous reinforcing agent (eg glass fiber)
Is preferable, and the combination of the glass fiber or carbon fiber and the granular and / or plate-like filler is a preferable combination particularly in terms of mechanical strength, dimensional accuracy, electrical properties and the like.

When using these fillers, it is desirable to use a sizing agent or a surface treatment agent if necessary. Examples of this are functional compounds such as epoxy compounds, isocyanate compounds, silane compounds and titanate compounds.

These compounds may be used after being subjected to a surface treatment or a convergence treatment in advance, or may be added simultaneously with the preparation of the material.

Further, the composition used in the post base of the present invention includes known substances generally added to thermoplastic resins and thermosetting resins, that is, stabilizers such as antioxidants and ultraviolet absorbers, flame retardants, and dyes. A colorant such as a pigment or a pigment, a lubricant, a crystallization accelerator (nucleating agent), and the like can be appropriately added depending on the required performance.

The post base of the present invention can be produced extremely economically by a conventionally known method such as injection molding. For example, polyarylene sulfide resin is blended with desired additives, melt-kneaded with an extruder to prepare pellets, and then molded, a pellet having a different composition is once prepared, and a predetermined amount of this is mixed and subjected to molding. A method for obtaining a post base having a composition, a method for directly charging one or more components of a target composition into a molding machine, and then obtaining a post base having a target composition,
Either is possible.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to Examples.
The present invention is not limited to this.

Examples 1 to 8 and Comparative Examples 1 to 6 A polyphenylene sulfide resin, a carbon-based substance, and
Other inorganic fillers were mixed in the proportions shown in Table 1 and melt-kneaded by an extruder to prepare a polyphenylene sulfide resin composition having a surface resistivity of 10 ¹⁰ Ω or less. For comparison, a polyphenylene sulfide resin composition having a surface resistivity of more than 1 × 10 ¹⁰ Ω and a composition having a surface resistivity of 10 ¹⁰ Ω or less prepared by mixing a polyamide resin with a carbon-based substance were also prepared. The composition obtained by blending a polyamide resin with a carbon-based substance was insufficient in terms of thermal stability, mechanical properties, dimensional accuracy, dimensional stability, press-fitting characteristics and the like.

Test pieces were prepared by injection molding using these pellets, and the following evaluations were performed.

General physical properties Tensile strength Measured according to ASTM D638 Bending elastic modulus Measured according to ASTM D790 Surface resistivity Measured according to ASTM D257 Dimensional accuracy ASTM The mold shrinkage when a tensile test piece was molded was measured.

Dimensional stability After leaving the ASTM tensile test piece for 5 days in a constant temperature and humidity chamber at 70 ℃ and 80% RH, measure the dimensional change in the flow direction when returning to room temperature (23 ℃) and compare it with the original length. The ratio was calculated as the rate of change (%).

Metal press-fitting characteristics A 5 mm-thick test piece was cut to form a hole with a diameter of 2.95 mm, a stainless steel pin with a diameter of 3 mm was press-fitted, and the pull-out strength was measured.

 It should be noted that none of the test pieces cracked during press fitting.

 The results are shown in Table 1.

Incidentally, posts were mounted on a post base injection-molded from the compositions of Examples and Comparative Examples, and a tape running test was carried out. There were few scratches on the tape and it showed extremely excellent tape running performance. On the other hand, Comparative Examples 1, 3, 5
Since the tape made of was composed of tape sticking to the rotating post, the torque fluctuation was large, and scratches on the tape were observed, which was probably due to the adhesion of dust.

Also, the tape of Comparative Example 2 had unevenness in winding the tape, and the tape running property was extremely unstable.

Further, in Comparative Examples 4 and 6, injection molding was difficult.

As is clear from the above examples, the post base according to the present invention has excellent strength, rigidity, and electrical characteristics, and also has good dimensional accuracy and dimensional stability, and therefore enables stable tape running. It is considered to be very practical.

[Advantages of the Invention] The post base of the present invention comprising a polyarylene sulfide resin molded product having a surface electrical resistivity of 1 × 10 ¹ to 1 × 10 ¹⁰ Ω has high strength, good dimensional accuracy and dimensional stability against heat and humidity. In addition, because it has excellent press-fitting characteristics and tapping workability, posts can be easily and firmly attached with high precision, and the running property of the tape guided by such posts is extremely stable over a long period of time. Hold.

Further, since the post base according to the invention of the present application has an electric resistance (surface electric resistivity) of a specific value or less as compared with general plastics, static electricity generated in the posts by the running of the tape is released and removed. This has the advantage of preventing adverse effects on sound quality, image quality, etc. due to static electricity or dust adhering due to static electricity.

Further, the post base made of such a polyarylene sulfide resin can be easily prepared by a conventionally known economical method such as injection molding, and further, the attachment of the posts to the post base can be easily performed by press fitting or the like. Since it is possible by the method, there is also an advantage that the manufacturing cost is remarkably lower than that in the case of processing the conventional metal.

The effect of the present invention has been achieved for the first time by using a specific polyarylene sulfide resin for the post base, and cannot be achieved at all with other resins.

[Brief description of drawings]

FIG. 1 is a perspective view showing one embodiment of a VTR post base and posts. Further, FIG. 2 is a schematic view showing a part where the parts of FIG. 1 are incorporated into the main body device and the tape is set. 1 ... Post base 2,2 '... Rotating post 3,3' ... Inclined post 4 ... Cylinder 5,5 '... Impedance roller 6 ... Erase head 7 ... Audio control head 8,8' ... Limited post 9 …… Tension post 10 …… Pinch roller 11 …… Capstan 12 …… Supply reel 13 …… Take-up reel 14 …… Cassette

Claims (4)

(57) [Claims] 1. A post base for fixing posts for guiding tape running of a recording / reproducing apparatus using a magnetic tape, wherein a carbon-based conductive substance is mixed with a resin whose base is mainly polyarylene sulfide. 1 x 10 ¹ ~
A post base comprising a resin molded product having a surface electric resistivity of 1 × 10 ¹⁰ Ω. 2. The post base according to claim 1, wherein the carbon-based conductive substance is at least one selected from carbon fiber and conductive carbon black. 3. The post base according to claim 1 or 2, wherein the resin molded product contains an inorganic filler other than the carbonaceous substance. 4. The polyarylene sulfide is polyphenylene sulfide, and the scope of claims 1 to 3.
The post base according to any one of paragraphs.