JPH0664690B2 - Button type floppy head - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a button type floppy head.

2. Related Art and its Problems Button-type floppy heads as shown in FIGS. 5 to 7 are known.

In this head, as shown in the figure, a slider 41, 45 made of non-magnetic ceramic is integrated with a head core 3 in which an erase core and a read / write core are integrated via a support body to form a head unit. Then, this unit is adhered to a resin button type housing 20, and the sliding surface is finished into a spherical surface to be manufactured. In this case, the sliding surface is formed only by the sliders 41 and 45 and the head core 3.

However, in such a conventional button type floppy head, the slider and the housing are separate bodies, so that the number of parts is large and the number of manufacturing steps is also large.

As the slider, non-magnetic ferrite, barium titanate, etc. are used in consideration of functionality, especially wear resistance.However, these materials are complicated to manufacture, and grinding / grinding during secondary processing Polishing is not easy, the manufacturing process is complicated, and the cost is high.

On the other hand, it is possible to use a housing in which the slider portion is integrated from various resins such as polyacetal which can be injection-molded and is easy to manufacture.

However, these molded members have inferior wear resistance, require further grindability during secondary processing, and have many so-called whiskers, which are scratched on the ground end surface.

By the way, polyphenylene sulfide is known as a material having extremely excellent wear resistance and good injection moldability.

This polyphenylene sulfide is a stable crystalline resin, which has extremely high physical properties among thermoplastic resins,
It is the most widely used engineering plastic for mechanical parts that require synthesis and durability, electrical parts that require heat resistance and incombustibility, and various chemical devices that require corrosion resistance.

However, the polyphenylene sulfide resin alone cannot provide the same wear resistance as that of the head core and prevent uneven wear.

In order to deal with such problems, prevent uneven wear,
A wear resistant filler or the like for improving the grinding / polishing property may be added to the polyphenylene sulfide resin and molded.

However, conventional polyphenylene sulfide is
When adding these additives, there is the disadvantage that the dispersibility is poor.

Therefore, ordinary polyphenylene sulfide has a problem that it is not possible to add 50% by weight or more of the wear-resistant fillers required for its properties.

Further, since the resin alone has a high electric resistance, there is a problem that spark noise occurs during traveling.

In order to deal with such a problem, various additives such as a conductive agent for preventing charging spark noise may be added to the polyphenylene sulfide resin and molded.

However, as described above, the conventional polyphenylene sulfide has the disadvantage of poor dispersibility when these additives are added.

In addition, polyphenylene sulfide has a disadvantage that a resin polymer is thermally decomposed during molding, sulfurous acid gas and the like are generated, and a molding die and a molding machine are corroded.

Furthermore, there is a drawback that the releasability at the time of molding is not good.

Therefore, a head using a housing in which a slider part is integrated with a resin molded body has not yet been put to practical use.

II Object of the Invention The object of the present invention is to have a resin housing that is integrated with a slider part that has excellent wear resistance and that has good grinding / polishing properties / precision formability during secondary processing, and It is to provide an inexpensive button type floppy head.

In addition, the second invention aims to improve the thermal stability, mold releasability and conductivity during molding.

III Disclosure of Invention The invention as described above is achieved by the following invention.

That is, the first invention is a button type floppy head in which a housing contains a head core, wherein the housing comprises a first polyphenylene sulfide resin having a melt flow of 400 to 800 g / 10 min and a melt flow of 2000.
It is a molded product containing a second polyphenylene sulfide resin of 10000 g / 10 min and quartz glass, and 0.5 to 2.5 parts by weight of the second polyphenylene sulfide resin per 1 part by weight of the first polyphenylene sulfide resin. It is a button type floppy head characterized in that.

A second invention is a button type floppy head in which a head core is stored in a housing, wherein the housing has a melt flow of 400 to 800 g / 10 min of the first polyphenylene sulfide resin and a melt flow of 2000.
Up to 10,000 g / 10 min of the second polyphenylene sulfide resin and quartz glass, and at least one of an antistatic agent, a stabilizer and a release agent, and the second polyphenylene sulfide resin per 1 part by weight of the second polyphenylene sulfide resin. A polyphenylene sulfide resin of 0.5 to 2.5 parts by weight is contained in the button type floppy head.

IV Specific Structure of the Invention A specific structure of the present invention will be described in detail below.

1 to 4 show an embodiment of the present invention.

The head core used is a so-called laminate type tunnel erase type in the illustrated example.

That is, the bonded body of the read / write core 31 formed of ferrite or the like and the support body 32 formed of non-magnetic ceramic such as barium titanate is supported by the erase cores 33 and 35 formed of the same kind of material as these, respectively. Body 34,36
It is sandwiched and laminated with the bonded body.

Note that, unlike the one shown, a so-called bulk type tunnel erase type or the like can also be used.

Such a head core is finally wound, and a back core is attached if necessary, and is bonded to a housing 2 described later. However, unlike the conventional case, the slider is not separately fixed to the head unit.

The housing 2 used is of a so-called button type and has a bowl shape. Then, as shown in FIG. 3, a cavity 25 for inserting a head core is provided on the upper surface.

As shown in FIG. 4, a head core is inserted into and bonded to the hollow portion 25 of the housing 2 as described above.

Then, as shown in FIG. 1, the sliding surface which is a flat surface.
The head is manufactured by polishing so as to form a curved surface 22 that is connected to 21 and the winding and back core.

That is, in the housing 2 of the present invention, the sliding surface 21 is integrated with the main body. Such a housing 2
Is a first polyphenylene sulfide resin with a melt flow of 400 to 800 g / 10 min and a melt flow of 2000 to 10000 g /
It is composed of a molded body containing 10 minutes of the second polyphenylene sulfide resin and quartz glass. The polyphenylene sulfide resin and quartz glass, which are the composition of the molded body, will be described in detail below. The polyphenylene sulfide resin has a linear structure as shown below, that is,
Thermoplastic resin of crystalline chain polymer, heat resistance, flame retardance,
Shows extremely high physical properties such as chemical resistance.

This resin composition has a melt flow of 4 according to ASTM standard D1238.
00-800 g / 10 min, more preferably 550-750 g / 10 min of the first polyphenylene sulfide resin, and melt flow 20000-10000 g / 10 min, more preferably 3000-8000 g /
It is composed mainly of a mixture of 10 minutes of a second polyphenylene sulfide resin.

When a melt flow of less than 400 g / 10 min is used as the first polyphenylene sulfide resin, physical properties such as mechanical strength and hardness are improved, but on the other hand, dispersibility is deteriorated and fluidity of the resin during molding is deteriorated. Not preferable for molding.

If the melt flow exceeds 800 g / 10 min, moldability and grindability are deteriorated and mechanical strength is lowered.

If the melt flow of less than 2000 g / 10 min is used as the second polyphenylene sulfide resin, the fluidity at the time of molding becomes poor, and additives such as quartz glass cannot be added, which is not preferable.

On the other hand, if the melt flow exceeds 10,000 g / 10 min, moldability, grindability and mechanical strength are deteriorated, and electrical properties are also deteriorated.

Two or more kinds of the first and second polyphenylene sulfide resins can be used respectively.

Furthermore, the mixing ratio of these first and second resins is the first
The second polyphenylene sulfide resin is contained in an amount of 0.5 to 2.5 parts by weight, and more preferably 1.0 to 1.5 parts by weight, per 1 part by weight of the polyphenylene sulfide resin.

The compounding ratio within such a range may be appropriately determined in consideration of the physical property value of the target dummy block, the addition amount of the filler, and the moldability.

When the amount of the first polyphenylene sulfide resin is large, the moldability is deteriorated, and when the amount of the second polyphenylene sulfide resin is large, the workability is deteriorated.

The resins of these polyphenylene sulfide resins are usually in the form of powder, and the average particle size of the resins of the first and second polyphenylene sulfide resins is about 50 to 500 μm, respectively.

Other physical properties of the resin of the first polyphenylene sulfide resin include a melting point of about 270 to 290 ° C, 815 ° C, 75
Mineral ash of about 0.1 to 2% by weight is suitable.

Similarly, other physical properties of the resin of the second polyphenylene sulfide resin include a melting point of about 270 to 290 ° C.
Ashes having an ash content of 0.1 to 2% by weight at 5 ° C. for 75 minutes are suitable.

Further, the molded body of the housing 2 contains quartz glass as a composition component.

This quartz glass has a wear resistance of the molded body of the housing 2,
It is used for the purpose of improving mechanical strength and grindability.

This quartz glass is a glass containing 98% or more of silicon dioxide.

The content of the magnetic head assembly member of the present invention is 2 to 6 parts by weight, more preferably 3 to 5 parts by weight, with respect to 1 part by weight of the first polyphenylene sulfide resin. is there.

The quartz glass having an average particle size of 0.03 to 0.15 mm is preferably used, and more preferably 0.05 to 0.1 mm.

The thermal expansion coefficient of quartz glass is usually 5.5~5.8 × 10 ^{- 7} de
A value of about g ^{- 1} is extremely smaller than that of ordinary glass.

Therefore, the load due to the thermal expansion of the quartz glass can be reduced in the molding machine cylinder during molding. Therefore, the addition amount can be increased as compared with general glass.

Such quartz glass includes a transparent product and an opaque product, and both can be used.

Further, in addition to these additives, it is preferable to add an antistatic agent, a stabilizer and a releasing agent.

By incorporating an antistatic agent such as a carbon filler as a composition component of the molded product, the conductivity of the molded product can be increased.

Therefore, it is possible to completely prevent the charging spark noise generated when the floppy disk is running.

As a form of the carbon filler to be contained, a powder form, a fiber form, a flake form, or the like is used.

These may be used alone or in combination of two or more depending on the purpose.

The content of these carbon fillers is 0.05 to 0.5 parts by weight, and more preferably 0.1 to 0.3 parts by weight, based on 1 part by weight of the first polyphenylene sulfide resin.

Further, by containing a stabilizer as a composition component of the molded body, generation of a metal corrosive gas such as sulfurous acid gas due to thermal decomposition of the resin polymer can be prevented during molding.

Therefore, it is possible to prevent the corrosion of the metal surface of the molding die and the molding machine, and the working environment becomes better. And by these, maintenance of a metal mold etc. becomes easy and moreover, the service life of these metal molds etc. is extended.

Further, this stabilizer can prevent deterioration (deterioration due to heat, light, oxygen, chemicals, bacteria, etc.) during long-term storage or practical use of the molded product after molding.

The content of the stabilizer is 0.0005 to 0.07 part by weight, and more preferably 0.001 to 0.04 part by weight, relative to 1 part by weight of the first polyphenylene sulfide resin.

As such a stabilizer, one or more kinds of aliphatic carboxylic acids and carbonates are suitable.

The aliphatic carboxylic acid salt may be a monovalent or divalent saturated or unsaturated mono- or dibasic acid having 2 to 30 carbon atoms.
Valuable metal salts are preferred.

More specifically, dibasic lead stearate, lead stabilizers such as lead stearate, cadmium stearate, cadmium laurate, cadmium stabilizers such as cadmium ricinoleate, barium stearate, barium laurate, ricinoleic acid. Barium-type stabilizers such as barium, calcium-type stabilizers such as calcium stearate and calcium laurate, lithium-type stabilizers such as lithium stearate, lithium laurate and lithium ricinoleate, zinc-type stabilizers such as zinc stearate and zinc octylate. Agent, dibutyltin laurate,
One or more tin stabilizers such as dioctyl tin laurate and dibutyl tin malate are used in combination.

Further, a carbonate may be used instead of or in addition to these.

Carbonate is a metal salt of carbonic acid, for example, one or more of zinc carbonate, calcium carbonate, lithium carbonate, and the like.

In addition to these, other stabilizers, if necessary,
Heat stabilizers such as epoxy compounds, organic phosphites, tribasic lead sulfate (tribase), and basic lead silicates, mono-, bis-, triphenols, aromatic amines, organic polysulfides, sulfoxides, phosphites An antioxidant stabilizer composed of an aromatic amine, an acid amide, a hydrazide, etc., a light stabilizer composed of hydroxybenzophenones, benzotriazoles, salicylates, and acrylonitrile derivatives may be contained.

Furthermore, by incorporating a mold release agent as a composition component of the molded product, the mold releasability of the molded product during molding can be improved. Therefore, it is possible to prevent damage to the mold and the like and the generation of defective products due to mold release troubles during molding. Further, the molding cycle can be increased, and the molded body can be manufactured at low cost.

The content of the release agent is 0.01 to 0.15 part by weight, and more preferably 0.04 to 0.1 part by weight, based on 1 part by weight of the first polyphenylene sulfide resin.

This release agent is an olefin resin such as polyethylene or polypropylene, a silicone resin, a silicone oil,
One or more of silicone resins such as silicone rubber and liquid paraffin are used in combination.

Further, if necessary, a lubricant and a coloring agent can be contained. The contents of these may be appropriately determined in consideration of the desired molded product and moldability.

In order to manufacture the housing 2 composed of the molded body of the composition as described above, predetermined amounts of the respective components are mixed, kneaded, and then molded.

As the molding method, injection molding, compression (press) molding, transfer molding and the like are used, but the injection molding method is preferable in view of productivity and the like.

Further, it is preferable to anneal the molded product after molding. This annealing can change the physical properties of the molded product and control the crystallization by annealing according to the required characteristics of the product. For example, crystallization improves the dimensional reproducibility and eliminates sink marks and warpage. It has the effect of increasing impact strength.

The annealing temperature is about 150 to 250 ° C.

V Specific Actions and Effects of the Invention According to the present invention, since the slider of barium titanate or the like is not used, the number of parts is reduced. Also, since the slider bonding process is eliminated and the slider grinding / polishing process is eliminated,
The productivity is improved significantly, the yield is improved, and the manufacturing cost is reduced.

Moreover, it has the same wear resistance as the conventional one.

More specifically, according to the first aspect of the present invention, the housing having a head sliding surface includes a first polyphenylene sulfide resin having a melt flow of 400 to 800 g / 10 min and a second polyphenylene sulfide resin having a melt flow of 2000 to 10000 g / 10 min. It is formed by molding containing a sulfide resin and quartz glass. A magnetic head having such a molded body has excellent precision moldability, excellent grinding / polishing properties during secondary processing, and greatly improves productivity. Moreover, since this molded body has excellent wear resistance, even if it is used for a long period of time after being assembled as a magnetic head, problems such as uneven wear do not occur. And, the precision moldability is extremely good.

Furthermore, since this housing is made of a resin molded body that can be injection-molded, there is an effect that the cost of the member can be reduced and the product cost can be reduced.

In addition, the second invention contains at least one of an antistatic agent, a stabilizer and a release agent in addition to the composition component of the molded article of the first invention, so that the effect of the first invention is obtained. In addition to this, the conductivity of the molded body can be increased if necessary. Therefore, it is possible to completely prevent the charging spark noise generated when the head is running.

Further, when a stabilizer is contained, generation of a metal corrosive gas such as sulfurous acid gas due to thermal decomposition of the resin polymer can be prevented during molding of this member. Therefore, it is possible to prevent corrosion of metal surfaces such as molding dies and molding machines,
In addition, the working environment will be better.

Therefore, maintenance of molds, molding machines, etc. is also easy,
Moreover, the service life of the mold and the equipment around it can be extended.

Moreover, when a release agent is contained, the releasability of the molded product can be improved. Therefore, it is possible to prevent damage to the mold and the like and the generation of defective products due to mold release troubles during molding. Further, the molding cycle can be increased, and the molded body can be manufactured at low cost.

VI Specific Examples of the Invention Specific examples of the present invention are described below.

(Example 1) As a composition of the molded body of the housing, a melt flow of 650 g /
10 minutes, melting point 282 ° C, 850 °, 75 minutes ash 1% by weight of 1% by weight of 1st polyphenylene sulfide resin, 20 parts by weight, melt flow 4000 to 6000 g / 10 min, melting point 285 ° C, ash 1
The weight percentage of the second polyphenylene sulfide resin was 13 parts by weight, and the silica glass having an average particle diameter of 75 μm was 82 parts by weight.
This was fed into a kneader (kneader) and thoroughly kneaded at 50 rpm for 1 hour. Then, pellets were produced with an extruder (pelletizer).

Using these pellets, the molded body of the housing shown in FIG. 3 was molded by injection molding.

The injection molding conditions were a cylinder temperature of 330 ° C and a mold temperature of 150 ° C. Then, the molded body is subjected to 200 in air.
Annealed at C for 3 hours. The shrinkage rate was 0.2%. Then, the head core was fixed to the housing having the above composition with an adhesive.

Then, the head front part was ground and polished like a figure.

Occurrence of chipping or breakage after polishing was observed for 100 molded articles, and no such occurrence was found.

Then, using this head, we actually conduct a running test,
The wear resistance of the head front and the occurrence of scratches on the medium were confirmed (Sample No. 1).

The abrasion resistance and the scratches were confirmed by using a commercially available floppy device, carrying out a 3 million pass running test, and then measuring the amount of wear (μm) on the sliding surface.

The results are shown in Table 1.

In addition, Table 1 shows an example in which only one kind of polyphenylene sulfide resin was used in Sample Nos. 3 and 4, and an example in which quartz glass was not contained in Sample No. 5.

Further, as samples No. to No. 10, samples were prepared in which polyphenylene sulfides having various melt flows shown in Table 1 were used in combination.

From Table 1, it can be seen that only the sample of the present invention exhibits good precision moldability and grinding / polishing property, and exhibits excellent properties such as durability in use.

In this case, sample No. 3 could not be molded because pellets were not formed during dispersion.

As a comparative example, a slider made of barium titanate was used (Sample No. 11).

(Example 2) 3 parts by weight of carbon powder having an average particle size of 30 mμm and a surface area of 950 m ² / g was used as an antistatic agent in the composition of the sample No. 1 of the molded body used in Example 1, an average property of 7 mμm, and an average aspect ratio. 1.5 parts by weight of carbon fiber having a ratio of 500 was added, and a molded body of the housing was molded in the same manner as in Example 1.

The method of confirming the improvement in conductivity was performed by preparing a head and using a commercially available VHS video device as in the case of Example 1. After continuously running for 5 minutes, the charge amount on the sliding contact surface of the molded product was measured. The measuring method was to install a charge amount measuring sensor at a position 1 mm away from the sliding contact surface, cut the tape at the same time when the running time of 5 minutes passed, and measure the maximum charging amount on the sliding contact surface.

As a result, the maximum charge amount was reduced by 99% as compared with the case of Example 1 containing no antistatic agent.

The workability and the amount of wear were the same as in the case of Sample No. 1 of Example 1.

(Example 3) 0.04 parts by weight of lithium stearate as a stabilizer was added to the composition of Sample No. 1 of the molded body used in Example 1, and a molded housing body was molded in the same manner as in Example 1.

The thermal stability of the molten resin at the time of molding was confirmed by visually comparing the degree of cloudiness of the mirror surface of the mold cavity with sulfurous acid gas.

That is, after performing continuous 1000 shots (molding cycle 20 sec, continuous operation for 6 hours) injection molding, the degree of cloudiness of the mirror surface of the mold cavity was compared with the state of the cavity mirror surface before injection molding. The mold cavity before injection molding was mirror-finished with a polishing agent after each injection molding of 1000 continuous shots of each compound. During this work, the degree of haze on the mirror surface of the mold cavity was confirmed.

As a result, clouding of the mold cavity could be clearly confirmed in the case of Example 1 containing no stabilizer, but clouding could not be confirmed in the case of this example.

The workability and the amount of wear were the same as in the case of Sample No. 1 of Example 1.

(Example 4) To the composition of the sample No. 1 of the molded body used in Example 1, 1.4 parts by weight of high-density polyethylene was added as a release agent, and a molded body of the housing was molded in the same manner as in Example 1. .

As a method for confirming the releasability, the ejection force when ejecting the molded body from the mold is measured, and the ejection of each sample is based on the case where the release agent is not added (Sample No. 1 of Example 1). The force ratio was calculated.

In the case of this example in which a release agent is added, the ejection force is 50 to 90%.
Diminished.

The workability and the amount of wear were the same as in the case of Sample No. 1 of Example 1.

From the results shown in Table 1 and Examples 2 to 4, the effect of the present invention is clear.

That is, according to the present invention, a large amount of quartz glass can be contained as the composition of the molded body of the housing.
Therefore, it has high wear resistance and high grinding / polishing properties and workability.

Further, since the molded body of the present invention can contain an appropriate amount of carbon filler, it is possible to prevent the generation of charging spark noise during traveling.

Further, by containing an appropriate amount of the stabilizer, it is possible to prevent generation of a metal corrosive gas such as sulfurous acid gas due to thermal decomposition of the resin polymer during molding.

Furthermore, by properly containing a release agent, the releasability at the time of molding can be improved.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of the present invention. FIG. 2 is an exploded perspective view of the head core used in the present invention. FIG. 3 is a front view showing a case used in the present invention. FIG. 4 is a front view showing the head before polishing. FIG. 5 is a front view showing a conventional button type floppy head. FIG. 6 is a perspective view showing a conventional head core. FIG. 7 is a front view showing a conventional case. 2,20 …… Housing, 21 …… Sliding surface, 31 …… Reed core core, 32,34,36 …… Support plate, 33,35 …… Erase core

Claims (3)

[Claims] 1. A button type floppy head having a housing containing a head core, wherein the housing comprises a first polyphenylene sulfide resin having a melt flow of 400 to 800 g / 10 min and a melt flow of 2000.
It is a molded product containing a second polyphenylene sulfide resin of 10000 g / 10 min and quartz glass, and 0.5 to 2.5 parts by weight of the second polyphenylene sulfide resin per 1 part by weight of the first polyphenylene sulfide resin. A button-type floppy head characterized by this. 2. The button type floppy head according to claim 1, wherein the housing has a sliding surface integrated with the main body as a top surface. 3. A button type floppy head having a housing containing a head core, wherein the housing comprises a first polyphenylene sulfide resin having a melt flow of 400 to 800 g / 10 min and a melt flow of 2000.
Up to 10,000 g / 10 min of the second polyphenylene sulfide resin and quartz glass, and at least one of an antistatic agent, a stabilizer and a release agent, and the second polyphenylene sulfide resin per 1 part by weight of the second polyphenylene sulfide resin. A button type floppy head comprising 0.5 to 2.5 parts by weight of the polyphenylene sulfide resin.