JPS6367262B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a high-density information carrier.

In Japanese Patent Application No. 55-48409, the present applicant proposed a method of recording signals by substantially providing magnetic portions and non-magnetic portions alternately. As a method for manufacturing an information carrier based on such a signal recording method, a thermoplastic resin is used as the material of the information carrier, a concavo-convex signal is formed on the thermoplastic resin through a thermal cycle, and a concavo-convex signal is formed on the concavo-convex surface by vapor deposition or sputtering. The applicant has already proposed a method of providing a magnetic layer, or a method of filling the recess with a resin liquid mixed with magnetic powder and curing it, but in such a manufacturing method, information It has the disadvantage that it requires a large amount of heat and time because the thermoplastic resin that is the material of the carrier is heated and melted and molded, and furthermore, a magnetic part must be placed on the surface after molding, making the process two steps. It also has some drawbacks.

Recently, a manufacturing method using ultraviolet curable resin instead of thermoplastic resin has become known in order to shorten molding time, but even this method requires two steps to form a magnetic layer after molding, which reduces production efficiency. Bad shortcomings have not been improved.

The present invention has been made to solve the above-mentioned drawbacks of the prior art, and is directed to an information carrier (hereinafter simply referred to as a magnetic information carrier) in which a signal is recorded by substantially providing magnetic portions and non-magnetic portions alternately. ), an ultraviolet curable resin containing a desired amount of magnetic fine powder is applied to the surface of an umbrella-shaped substrate that transmits ultraviolet rays, and this is used as a material for the magnetic information carrier; A stamper having a negative signal with respect to the final signal to be obtained is gradually pressed onto the ultraviolet curing resin coating layer containing magnetic fine powder from the top of the umbrella shape to the periphery, and the stamper and ultraviolet light containing the magnetic fine powder are applied. After the curable resin coating layer is completely adhered, the signal is molded by irradiating ultraviolet rays.

Next, the present invention will be explained with reference to FIGS. 1 to 3, which are examples thereof.

In the present invention, a circular plate serving as the base material 1a of the information recording carrier is prepared in advance by molding, and an ultraviolet curable resin mixed with a desired amount of magnetic fine powder is applied to the convex surface of the circular plate to form a carrier material. 1 and a signal is formed on this coating layer 1b.

Regarding the material of the circular plate serving as the base material 1a, a material that has good adhesion to the ultraviolet curable resin mixed with a desired amount of magnetic fine powder, which will be described later, and that transmits ultraviolet rays well, such as a plastic that transmits ultraviolet rays such as polycarbonate or polypropylene, is used. Good to use.

The important thing when molding the base material 1a is that the base material 1
Rather than molding a into a flat plate shape, it is made into an umbrella shape in advance. In other words, it is formed like a part of a sphere, with the central part as the apex and the peripheral parts as the base. The base material 1a made in this way is shown in FIG.

Note that the vertical and horizontal ratios have been changed here for clarity.

An ultraviolet curable resin mixed with a desired amount of magnetic fine powder is thinly and uniformly applied to the entire surface of the convex surface of the base material 1a prepared in this way by a method such as roll coating or spin coating. This ultraviolet curable resin mixed with a desired amount of magnetic fine powder is mainly composed of a prepolymer having a radically polymerizable unsaturated group and a monomer having an ethylenically unsaturated group, to which a small amount of a polymerization initiator and an auxiliary agent are added. Magnetic fine powder such as Fe, Ni, Co is contained in the ultraviolet curable resin.
A desired amount of fine powder of metals, oxides thereof, alloys thereof, oxides of alloys thereof, etc. is added in a desired amount and thoroughly mixed and dispersed.

Next, such a material 1 is fed out to a press machine. As is clear from FIGS. 2 and 3, this press machine has a lower mold 3 and an upper mold 5. The lower mold 3 is made of a material that transmits ultraviolet rays, such as ultraviolet transparent glass, and its upper surface is is provided with a tightening ring 2 for fixing the periphery of the material 1, and the upper mold 5 is provided with a stamper fastener 8 for attaching a stamp bar 7. Also, 1
0 is the ultraviolet light source located below the lower mold 3, 4 is the upper mold 5
It is a hydraulic press for upper and lower parts, and 9 is a centering button.

The material 1 described above is placed on the upper surface of the lower die 3 of the press machine as described above, with the coating layer 1b facing upward, and the tightening ring 2 is used to position the material 1 and fix its peripheral edge. At this time, since the upper surface of the lower mold 3 is formed in a flat shape, the material 1 contacts the lower mold 3 only at the peripheral edge, and the top of the material 1 must not touch the lower mold 3 and float slightly. This state is shown in FIG. After that, when pressure is applied while raising the lower die in the hydraulic press, the contact between the coated layer 1b and the stamper 7 attached to the upper die 5 of the press is caused to occur at the center, that is, the top of the coated layer 1b. At first, it becomes a point contact, and as the contact progresses while slightly deforming the material 1 toward the outer periphery, air is pushed out,
Air bubbles are prevented from entering between the coating layer 1b and the stamper 7. At the same time, it goes without saying that the air between the material 1 and the upper surface of the lower mold 3 escapes from the periphery as pressure is applied. In this state, pressure is applied to the specified pressure by the hydraulic press, and when the specified pressure is reached, the shutter 6 of the ultraviolet light source 10 installed at the bottom of the lower mold is opened to irradiate the coating layer 1b with ultraviolet rays. Mold curing is completed. In this case, unlike the case of molding by recycling heating and cooling, curing of the resin is completed almost instantly, so it is possible to significantly shorten the time compared to the case of thermal recycling. When curing by ultraviolet rays is completed and the hydraulic press 4 is opened, an information recording carrier in which information signals are transferred and molded onto the ultraviolet curable resin coating layer 1b containing magnetic fine powder on the surface is obtained. Here, the material 1, which was initially shaped like an umbrella, was deformed into a flat shape by pressure, and in addition, the pressure was released due to the shrinkage that occurs when the ultraviolet curable resin containing magnetic fine powder is cured. However, the return of the deformation is very small and the shape becomes almost flat.

With this configuration, the information recording carrier can be manufactured quickly and with stable quality without inclusion of air bubbles.

The feature of the present invention is that the base material 1a is formed in advance into an umbrella shape, and a thin coating layer 1b of ultraviolet curable resin containing a desired amount of magnetic fine powder is provided on the convex surface of the base material 1a, and ultraviolet rays are irradiated under pressure. This coating layer 1b
The signal is transferred and molded into the image. What is important here is that by forming the material 1 into an umbrella shape in advance, pressure can be applied while displacing air during pressurization, and air entrainment can therefore be completely prevented.

Although the material 1 has been formed into an umbrella shape, a coating layer 1b of an ultraviolet curable resin containing a desired amount of magnetic fine powder is provided on the convex surface of the material 1.
The signal is transferred and molded by UV irradiation while pressurizing the signal 1b, and the coating layer 1b of the UV curable resin containing a desired amount of magnetic fine powder shrinks slightly when the signal molding is completed, so it is shaped like an umbrella. The direction is to loosen the curvature of.

In addition, the umbrella shape is deformed into a flat shape by applying pressure, and after the pressure is released, the umbrella shape becomes almost flat, and even if it does return, it will be at a level that does not hinder reproduction. By the way, according to experiments conducted by the present inventors, there is a difference in height between the center and the outermost periphery of the base material 1a prepared in advance using an information recording carrier with a diameter of 120 mm and a thickness of 0.5 mm (difference between the top and bottom of the umbrella shape). of
If it is 80μ, the height difference after signal molding is 30μ
It had decreased to a level that did not pose a problem for signal reproduction.

Another feature of the present invention is that conventionally, shaping the signal and imparting magnetism were performed in two steps, but with the present invention, they can be performed simultaneously, simplifying work, shortening manufacturing time, and reducing energy consumption. etc. can be achieved.

Furthermore, another feature is that an ultraviolet curable resin containing magnetic fine powder is applied to the base material 1a molded into an umbrella shape to a thickness necessary for molding, and this is used as the molding layer 1b, thereby reducing the amount of resin used. In addition, by strictly controlling the quality of the ultraviolet curable resin containing this magnetic fine powder and coating it, it is possible to manufacture high-quality information recording carriers. It is possible to mold a signal with a magnetic layer. Here, the thinner the molding layer 1b is, the shorter the molding time can be. However, as a result of various experiments, in order to obtain a stable information recording carrier of good quality, the thickness of the molding layer 1b containing the magnetic fine powder is The depth must be at least 10 times the depth of the unevenness of the signal to be molded, and the content of magnetic fine powder mixed in the ultraviolet curable resin must be kept to 60% or less (preferably 30 to 40%). I came to the conclusion that there is.

Magnetic fine powder is opaque to ultraviolet light, but
Since the thickness of the ultraviolet curable resin layer is thin, it is sufficiently cured by an ultraviolet light source, so there is no problem.

Specifically, when the signal depth is 1000 to 1500 Å, the thickness of the molded layer 1b is 1.0 to 1.5 μm or more.

Furthermore, the particle size of the magnetic powder is closely related to the signal depth, and is suitably 1/5 or less of the signal depth.

Therefore, when the signal depth is 1000 to 1500 Å, the particle size of the magnetic powder contained in the ultraviolet curable resin is 200 to 300 Å.
Å (0.02 to 0.03μ) is appropriate.

In addition, the relationship between the thickness of the molded layer 1b and the thickness of the base material 1a is also important.
The thickness a must be sufficiently thicker than the thickness of the molded layer 1b.

In view of this, the present inventors conducted various experiments on the relationship between the thickness of the base material 1a and the thickness of the molded layer 1b, and found that the thickness of the base material 1a needs to be at least 50 times the thickness of the molded layer 1b, preferably 100 times or more. It was concluded that the thickness was appropriate. Therefore, in the case of a magnetic information recording carrier, the thickness of the base material 1a is 0.05 mm or more (preferably 0.1 mm or more).
A thickness of 0.2 to 0.3 mm is appropriate.

The thickness of the molded layer 1b in this case is 1 to 1.5 microns, but preferably 2 to 3 microns.

As described above, according to the manufacturing method of the present invention, the manufacturing process that required 20 to 30 seconds in the conventional technology can be reduced to 2 to 30 seconds.
Molding can be completed in 3 seconds, the number of manufacturing steps is reduced, work efficiency is improved, and magnetic information recording carriers of significantly superior quality can be manufactured without any negative effects due to the generation of bubbles. .

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is an explanatory diagram showing a base material serving as an information recording carrier.
A is a plan view thereof, B is a sectional view taken along the line A-A' in A, Fig. 2 is an explanatory diagram showing the state in which the material of the information recording carrier is set in the press, and Fig. 3 is the state at the time of molding. FIG. 1...Material, 2...Tightening ring, 3...Lower mold,
4... Hydraulic cylinder, 5... Upper die, 6... Shutter, 7... Stamper, 8... Stamper fastener, 9... Centering bush, 10... Ultraviolet light source.

Claims (1)

[Claims] 1. In a method for manufacturing a high-density information carrier in which signals are recorded by providing substantially magnetic portions and non-magnetic portions alternately, a desired amount is placed on the surface of an umbrella-shaped base material that transmits ultraviolet rays. An ultraviolet curable resin containing magnetic fine powder is coated to serve as the material for the high-density information carrier, and the ultraviolet curable resin coating layer containing the magnetic fine powder is coated with a layer of ultraviolet curable resin that is negative to the final signal to be obtained. A stamper having a signal is gradually pressed from the top of the umbrella shape to the periphery, and after the stamper and the ultraviolet curable resin coating layer containing the magnetic fine powder are in complete contact, irradiation with ultraviolet rays is performed to mold the signal. A method for producing a high-density information carrier characterized by: