JPS6020318A - Base material and its production and device therefor - Google Patents

Abstract

PURPOSE:To obtain a molding for a cylindrical recording medium which has a uniform wall thickness, is seamless and has good dimensional stability by feeding a resin sheet which is plasticized by heating to a vacuum forming machine and molding the sheet while holding the same with clamps around a male die provided with a vacuum means as well as heating and cooling means. CONSTITUTION:A thermoplastic resin sheet 1 of a polyethylene terephthalate, etc. is supported by clamps 2 and is plasticized by heating between heaters 3 and 3. The sheet 1 kept supported by the clamps 2 is fed to a vacuum forming machine. Plural vacuum holes 15 and a pneumatic hole 16 to be used in the stage of parting are provided to the vacuum forming machine and an inside pipe 25 and an outside pipe 26 for passing a medium for heating and cooling are provided thereto. A base body for a cylindrical recording medium is formed by using a male die 9 which is finished to a specular surface. The base material of which the wall thickness of the molding is 10-100mu, the coefft. sigman-1/x of fluctuation in the wall thickness distribution is <=0.2 and the surface roughness at the centerline of the inside surface is <=0.04mu is thereby obtd. The excellent cylindrical base body for magnetic recording which produces no noise is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a base material for a magnetic recording medium made of a cylindrical thermoplastic resin molded body, a method for manufacturing the same, and an apparatus thereof, and more particularly, a cylindrical molded product formed by vacuum forming a thermoplastic resin sheet. For recording media that has a uniform wall thickness, good dimensional stability, smooth surface, and seamless, breakable metal (used for iB memory and original memory). This invention relates to a base material, its manufacturing method 8, and its apparatus.

In recent years, in the field of magnetic recording, magnetic recording devices have become smaller, and the need for metal magnetic thin film media that can perform high-density recording has increased. γ-? In place of the coated type media of 203, metal magnetic thin film media based on Co alloy based on plating methods, vacuum evaporation, etc. have been investigated and some of them have been put into practical use.

However, the recording media used in magnetic memories, optical memories, etc. that have been proposed in the past are only tape-shaped or disk-shaped, and for example, images such as frame-by-frame recording of television image signals or normal recording, etc. These are the only devices that can be used for playback devices, audio recording and playback devices, digital recording and playback devices for electronic computers, flexible disks for electronic cameras, etc.

When recording television image signals field by field magnetically on one circumference of a recording medium, the inner circumference of the magnetic recording medium has a lower relative speed between the head and the disk than the outer circumference, so the outer circumference The image quality is lower than that of . However, when trying to obtain image quality above a certain level, there is a limit to the inner circumference that can be recorded due to the relative speed, and in order to increase the number of recorded images, it is necessary to increase the outer diameter. As a result, the diameter of the disk becomes thicker, and the entire magnetic recording Niyu device a becomes more compact.
The drawback is that it cannot be summarized in detail.

The present inventors have conducted various studies to solve the drawbacks of these methods, and as a result, we have created a cylindrical molded product with no seams by vacuum forming a thermoplastic resin sheet. It has been found that by coating the back side of the disk with a metal magnetic thin film, it is possible to perform high-speed recording, and the relative speed between the head and the disk can be kept almost constant.

Performance requirements for the base material of magnetic recording media used in magnetic memories and the like include (1) Thickness of lO to iuoμ with small thickness distribution.

(2) It must be smooth and free from defects such as seams, scratches, and bumps.

(3) The slope of the cylindrical part is small.

(4) There should be no deformation during the post-process of forming the magnetic thin film.

etc. can be mentioned.

Generally, a vacuum forming method has been proposed as a method for obtaining a cylindrical thermoplastic resin molded body.

For example, if the diameter (D) and height (L)σ) ratio L/D of the cylinder is less than 1, the cylindrical molded product can be formed by simply heating the cylinder and applying vacuum through the female mold. can be obtained. This type of molding is generally performed on polystyrene resin sheets. It's something. However, with such a forming method, the wall thickness distribution on the cylindrical side surface is large and a small wall thickness distribution (.sigma.) cannot be obtained. Also, L
/ σ) such that D is 1 or more, the meat nodule distribution becomes even thicker, and it becomes impossible to obtain a molded product that is sufficient for practical use7.
．． Cu. A so-called deep drawing cylindrical forming blade with L/D of 1 or more? There are various methods for A. For example, there is a molding method in which a heated sheet is first inflated by applying slight pressure to the air, then it is pushed up by a male mold, and then vacuum is drawn from the female mold, and at the same time, the sheet is pressed against the female mold using compressed air from the male mold. With this method, it is possible to obtain a cylindrical molded body with L/D of about 2, and the ci technique is to reduce the coefficient of variation of the wall thickness distribution on the side surface. However, with this method, the surface roughness (Ra) of the cylindrical molded body cannot be achieved to be less than 0.04 μm, and the undulations at a slightly larger period due to the flow of compressed air over the surface cannot be achieved. It is impossible.

Also, there is so-called male molding, in which a heated sheet is pushed up with a male mold, vacuum is applied from the side of the male mold, and the sheets are densely layered on the male mold. It is used in combination with a female mold compressor when foaming to about double the size and processing it into a sheet shape to form a so-called PSP to obtain a plastic foam molded product. This method is effective for forming sheets such as foamed sheets that are highly flexible but difficult to stretch, but when using this method for the purpose of the present invention, the following There is a problem like this.

(1) Deep drawing (L/I)) When forming as in 1), wrinkles appear on the top surface of the cylinder.

(2) Fold-like wrinkles appear near the opening on the side surface of the cylindrical molded body.

(3) When the male mold pushes up, the sheet is rubbed by the tip of the male mold, so streaks appear on the inside of the side surface JH of the cylindrical molded object, increasing the surface roughness.3, (4) Cylindrical molded object The wall thickness distribution on the side surface is large, and it is difficult to suppress the coefficient of variation to 0.2 or less.

Does the present invention solve these shortcomings? The purpose is to create a recording medium by vacuum forming a thermoplastic resin sheet (a base material for a magnetic recording medium consisting of a cylindrical molded body with suitable performance, a manufacturing method R therefor, and an apparatus for manufacturing the same). They are very talented in what they are trying to offer.

That is, the first invention of the present invention consists of a cylindrical molded body formed by a vacuum forming method and having a wall thickness of lO−100μ,
consisting of a cylindrical thermoplastic resin molded body, characterized in that: The base material for magnetic recording media (its second source) is vacuum formed from a thermoplastic resin sheet using a male die to form a cylindrical molded body. In the manufacturing method 1-6, the first =T plasticized by heating
The sheet is clamped by both conveying means and sent to a vacuum forming machine, and the sheet is heated while being held by a clamp that partially or completely compresses the sheet around a cylindrical male die. Is it sudden after vacuum forming with a male mold? g-tl-nito? The feature is a method for producing a cylindrical thermoplastic resin molded body, and the invention relates to an apparatus for manufacturing a cylindrical molded body by vacuum forming a thermoplastic resin sheet using a male mold. , a device for clamping the MfJ sheet around the male die, and a device that can be moved up and down to a position below the position where the sheet is clamped; 1. 1. An apparatus for producing a cylindrical thermoplastic resin molded body, comprising: a vacuum means and a heating/cooling means; .

The present invention will be further explained in detail below.

First of all, the first aspect of the present invention is to form n by a vacuum forming method.
A cylindrical thermoplastic resin molded body with a TC wall thickness of 1'0-100μσ, the coefficient of variation of the wall thickness distribution (σn”l/'
The substrate for a recording medium has X) of sail 2 or more F, preferably k"!, U, 1 or less, and the center surface roughness Ra) of the inner surface is preferably 0.4μ or less, preferably l), 01μ or less.

In this way, the wall thickness and wall thickness distribution Q of a cylindrical thermoplastic resin molded body, the coefficient of variation and the center line surface roughness of its inner surface are within the range shown below. This is because the gold AfS magnetic thin film cannot be used as a magnetic recording medium even if it goes bankrupt. To explain further, magnetic recording media usually have 4I! Sano 1 Rokin A1 Because the thickness of the magnetic thin film is extremely thin, the condition of the surface of the thermoplastic resin molding appears as unevenness on the magnetic recording medium/body.The unevenness on the magnetic recording medium is mainly Line surface roughness (Ra) and sail 0
If it exceeds 4μ, the noise level during magnetic recording and reproduction will become high, which is not preferable. Also, the wall thickness distribution of the cylindrical thermo-OT plastic resin molded body has a coefficient of variation! (11) If the range is exceeded, the contact state between the magnetic recording medium and the magnetic head changes, so it is preferable (1, <no).

The second invention is the manufacturing method of the first invention, and the third invention is a manufacturing apparatus thereof.

In the present invention, thermoplastic resins are those that do not deform at a stain temperature of 500 or less, and specific examples thereof include thermoplastic polyester resins, vinyl chloride <m resins, styrene resins,
Mixed resins such as polycarbonate resins, acrylic resins, and ILs that can be mixed with these resins are preferably medium-heatable polyesters.

In the present invention, the thermal 1llIT plastic resin sheet is made of the above-mentioned thermoplastic resin, and has a wall thickness of 30 to 30 mm.
It has a diameter of 0μ, preferably 50 to 200μ, and is of high quality with a smooth surface and no fish eyes or foreign matter contamination. In order to manufacture a cylindrical molded body using such a sheet, it is sufficient to preheat and mold the sheet using a specific male mold of a vacuum forming machine.

There are two types of methods for supplying thermoplastic resin sheets to vacuum forming machines: patch type and continuous type. Batch type is a method in which the sheet is cut to a certain size, clamped, preheated, and then supplied to the vacuum forming machine. The continuous method is a method in which a roll-shaped thermoplastic resin material is passed through a preheating zone and supplied to a vacuum forming machine.

The present invention will be explained below with reference to simplified figures. The drawings show an embodiment of the present invention, and FIG. 1 is an explanatory diagram of the device, and FIG.
The figure is an explanatory diagram of the male type, and FIG. 3 is an explanatory diagram of the piping of the male type heating and cooling means.

The apparatus of the invention is shown in FIG. 1 (A).

It consists of (B), (C) and each zone.

First, in the zone (A), the thermoplastic resin sheet 1 is fixed to the crank f2 and then moved to the heater 3 cup 7 (A), which has been preheated in zone (B), and the sheet 1 is molded f2. ; After heating to the temperature required for 6, zone (B) vc is retreated. At the same time, Flang 2
moves to the forming zone of zone (C) while holding the sheet. Although the sheet fixing and knife heating methods of the present invention may be the above-mentioned methods, they may be carried out by any other method of law. for example,
Using a winding roll, the width of the rolled out sheet is held between the flanges and moved intermittently through the heating zone to a predetermined temperature (heating 1-1), and transferred to zone b, where it is sequentially formed. Continuous molding is also possible. /-At the same time as the movement to zone (C) is completed, 6
Air cylinders 3 and 7 are activated, the knock plate 4 is lowered, and the preflang plate 5 is raised (the sheets are individually fixed around the male molds. In the case of flow molding, the sheet condition for each male mold is the same, and the difference in molding conditions between the male molds can be reduced. Another meaning of the above operation is that the sorting is fixed in a circular manner around each male mold, so that when the male mold pushes up in the other process, the sheet is spread evenly, and the result is 1- It is possible to make the wall thickness distribution in the circumferential direction of the 7t round cylindrical molded product as small as possible.

Furthermore, if a disc-shaped guide plate is provided on the upper part of the knock plate 4σ, the male mold will rise and the sheet will gradually slide into the male mold at a certain time. Then, the f-table 8 is raised by the hydraulic pressure, and the male die 9 lifts up the seat 1. At the same time, after a few seconds, the A-type 9Q is placed on the hem part. A vacuum pump connected to piping 10 applies vacuum through the provided vacuum hole to form the sheet into a male shape.When the male mold pushes up the sheet, the temperature of the male mold is low. During vacuum suction 1., the sheet solidifies too quickly, and not only is the mirror surface of the male die not sufficiently transferred, but the molded product is easily wrinkled, and the cylindrical molded product desired in the present invention is obtained. Therefore, it is preferable to heat the male mold to the temperature required for molding in advance. It varies depending on the type of sheet, but the general knowledge is that 50 to 150°C is preferable.
is 80-120°C. After molding is completed, the vacuum suction is continued and the blackness is maintained at this T blackness immediately or for up to several minutes. After this, pass cooling water through the male mold.
2) Cool the male mold and enter the mold release process. If the vacuum suction is stopped while the hot water temperature is still high, the molded product will be deformed (-1~1~, and a good product will not be obtained. In order to improve the sex of a mature woman, it is necessary to maintain the temperature of the male mold for up to several minutes after molding and perform hot sawing. By providing this, for the first time, it is possible to obtain a substantially cylindrical molded body for the purpose of the present invention in an industrially possible cycle.

117), @ speed 7J [] Sheet as a means of thermal cooling,
Various methods can be considered, but is it possible to quickly switch between steam or hot water and cold water to remove water inside the male mold? The circulation method is efficient.

Next, the male mold used in the present invention will be explained in more detail with reference to FIG.

The tip head 11 of the male die 9 is made of the same metal material as the male body or a heat insulating material. As the heat insulating material, for example, synthetic resin materials that can withstand relatively high temperatures, such as Bakelite and nylon, are used. If the male head 11 is made of a metal material, it is preferable to use a material whose corners are partially curved to an IR or better, and which are polished to a mirror surface. This is to make the part of the corner that comes into contact with the heated sheet as smooth as possible when the male mold pushes up the sheet, and to prevent scratches when the sheet slides.

Note that the 0111 surface portion 12 of the male mold main body has a slope of 2 degrees within 30 minutes for mold release after molding. The above does not meet the purpose as a cylindrical base material for a mountain memory medium.

At 10,000 yen, the side surface part 120 is finished to a super mirror surface with a surface roughness Ra of 0.04μ or less, and the inside of the side surface of the cylindrical molded body is made by transferring this super mirror surface to have the desired surface precision. When molded into a product 7, the surface of the side surface portion 12 is preferably subjected to a hardening treatment or a surface coating such that the hardness becomes 100 or more in terms of Picchus hardness. The reason for this is to prevent scratches from occurring when the molded product is released from the male mold. Is the side part of the male mold a magnetic film of a cylindrical molded body? It is necessary that the side part 12 corresponding to the part to be formed also has an extension part 13 of the same slope. The reason for this is to ensure that the thickness distribution of the side surface portion 12 used as a recording medium is completely within the above range. Yofkoso extension part 1
The length of 3 varies depending on the diameter of the molded object, but is usually 10 to 7.
A range of 0 m is appropriate. The lower part 14 of the side surface part may be formed into a curved surface with an appropriate radius within the range of 0 to 6 degrees from the horizontal plane, if necessary. The male die 9 is provided with a plurality of vacuum holes 15 inside so that it can suck the heated sheet.

The number and position thereof are arbitrary, but they cannot be provided on the side surface portion 12. In addition to the vacuum hole 15, a pressure air hole 16 is provided in one place where pressurized air is applied during mold release.

Next, vacuum forming is performed using a male mold, and a molded product may be provided with one or more male molds.

To heat the male mold 9, open the valves 18, 19'& 20 with the valves closed and steam or hot water must be supplied to the male mold through the manifold z2 (not shown). However, the humidity is controlled by controlling the steam pressure and, in the case of hot water, by the temperature controller.

The opening degree of the drainage side valve 21 can be appropriately controlled. To cool type 23b, valve 20 is closed, valve 19 is opened, and manifold 2 is cooled.
Valve 2 with water supplied to 2 and connected to male VC
1 is fully opened, and the cooling water collected in the manifold 23 is discharged from the male mold to the outside of the system. During reheating, valve 18 is opened with valves 19 and 20 closed, air is sent into manifold 22, residual water is discharged out of the system through manifold 23 and valve z1, and then valve 18 is closed. Then open valve zO and supply steam or hot water.

The male type is provided with a joint 24, and this joint is connected to two pipes 11 consisting of an inner pipe 2b and an outer pipe 26 in total, and a heat transfer medium supplied from a manifold 22. It passes through the joint 24, passes through the inner tube 25, enters the male mold, and returns from the outer tube 26 to the joint 2'IC.

As explained above, the base material made of the cylindrical thermoplastic resin molded body of the first uninvented invention is manufactured using a specific vacuum molding die, and therefore has an inner thickness of 10 to 100μ; The coefficient of variation is as small as 0.2 or less, and the centerline surface roughness of its inner surface is 0.2 or less. (Since it is 14μ or less, it is suitable as a base material for magnetic recording media.

Mano's second invention is to manufacture a cylindrical molded body by vacuum forming a thermoplastic 1-fat sheet using a male die, clamping the sheet around the cylindrical male die, and heating it in a closed state. This is a method for producing a recording medium substrate that is vacuum formed and then rapidly cooled.

Further, the third invention is an invention of a hn filtration device used in the manufacturing method of the second invention, and by using the uninvented device,
A substrate for a recording medium is obtained.

A more detailed explanation will be given below with reference to Examples.

Next, a description will be given of the process of actually manufacturing a cylindrical molded body using the apparatus of the present invention. A polyethylene terephthalate sheet having an average wall thickness of 1'30 μm was cut into a predetermined size VC and set in the crank f2 of the molding machine shown in FIG. Heat the sheet to a temperature that can be used for molding, and then transfer it to the molding zone.
” / sandwiched around the edges, and then heated with steam for 100CK
/JO Heat 1 piece, push up the male mold, and after 2 seconds apply vacuum suction from the male mold to form 1 piece. The Sadao type used here has a minimum diameter of 35 ropes at the top, a maximum diameter of 381 meters at the top, a cylindrical rod of 100 degrees Celsius, and a 41 (11-sided sieve of 8 degrees Celsius).
Partial surface roughness of 141, centerline average roughness of the surface of 0. After molding, the temperature of the male mold was kept at 1 (J OC) for 1 minute while vacuum suction was applied, and then the steam was removed from cold water to cool it sufficiently to obtain a cylindrical molded material f4-.

32L of the side part of this cylindrical molded body with a height of 8-Ora+
The average wall thickness (ma) measured around the rib I is 42μ, and the coefficient of variation of the wall thickness distribution (σn-+/x) is υ, ()8, indicating that it has a good thickness density. Ta. 11 between height 80 (
Center line average of the inner surface of the a-plane part #i Saku Ra) <4,
(J, (J l μ), and had extremely good properties.

Further, this cylindrical molded body was immersed in 80° C. flat water for 30 minutes, but no dimensional change was observed.

[Brief explanation of the drawing]

The drawing shows an embodiment υ of the present invention device? - “It is a thing,
Fig. 1 is a diagram showing the upper half of the mounting Tl, Fig. 2 is an explanatory diagram of the male type, and Fig. 3 is an explanatory diagram of the heating R and cooling means of the male type. What 1... Seat 2... Clamp 3... Heater 4... Dowel plate 5... Break clamp plate 6.7... Air cylinder 8
...Table 9...Male type 10...Piping 11...Male type head 12...Male type side part 13...
Male mold side part extension 14...Male mold side part D length part 1pu...Vacuum hole 16...pressure nitriding hole 1f1.19.20°22.23.
...Maniho 21...Balgould 24...Joint 25...Inner tube 26...Outer tube patent applicant Zeki Kagaku Kogyo Co., Ltd. Figure 1 B A S Figure 2 Procedures Amendment Book 1. Display of the case 1982 Patent Application No. 129043 2 Name of the invention Base material, its manufacturing method and its device 3 Person making the amendment Relationship with the case Patent applicant Address 1-4-1 Yurakucho, Chiyoda-ku, Tokyo Column 5 of Detailed Description of the Invention of the Specification, Contents of Amendment 5-1) Change “0.4μ” to page 9, line 14 of the specification by rO,0
4μ,” he corrected.

Claims (1)

[Claims] ■) The wall thickness formed by vacuum forming method is lO~100
A recording medium consisting of a cylindrical molded body of μ, the coefficient of variation (σn-, /x) of its wall thickness distribution is 0.2 or less, and the centerline surface roughness (Ra) of its inner surface is 0.04 μ or less Base material for use. 2) Method for producing a cylindrical molded body by molding a thermoplastic resin sheet using a male mold VC26ite, both ends of the sheet plasticized by heating are clamped to the feeding means and the sheet is completely molded. The sheet is sent to a molding machine, and then vacuum formed using a heated male mold while holding the sheet with a clamp that partially or entirely compresses the sheet around a cylindrical male mold, and then the male mold is cooled. A method for manufacturing a cylindrical thermo-OT plastic resin molded body with % characteristics. 3) A device for manufacturing a cylindrical molded product by vacuum forming a thermoplastic resin sheet using a male die 'f-2, which includes a device for clamping the sheet around the male die and a section F from the position where the sheet is clamped. Moved to the upper part of #J town north, provided a mold equipped with a vacuum means and a heat cooling means, and constructed so as to perform vacuum forming using the male mold with a tensile sheet. This is characterized by a cylindrical heat 0
Manufacturing equipment for engineered plastic resin moldings.