JPS5862021A - Manufacture of high density information record carrier - Google Patents

Abstract

PURPOSE:To obtain the titled carrier with the strain being prevented, by placing on a substrate an ultraviolet-curing resin having a specified viscosity value in the shape of a semisphere, bringing a stamper into contact with the resin under pressure to mold it under pressure, and irradiating it with ultraviolet rays to harden the resin. CONSTITUTION:The disc substrate 4 of an ultraviolet-permeable material (e.g. polyvinyl chloride) is placed on a bottom force 5 of an ultraviolet-permeable meterial, and the ultraviolet-curing type resin 3 having a viscosity of 100-700c. P. is dropped by a dispenser 7 on the center of the surface of the base material. Thereafter, the tip of the dispenser 7 is withdrawn quickly outside of the pressing section, and the stamper 2 of the top force 1 is lowered. The stamper 2 comes in contact with the semisphere-shaped resin 3 at a point, and a pressure of 5-50kg/cm<2> is applied to press and mold it in an annular shape. The resin 3 is finally brought to 1/20 times, preferably, 1/60 times or less as thick as the substrate 4. Ultraviolet rays are irradiated from an ultraviolet light source 6 to cure the resin and to mold signals.

Description

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

When molding a high-density information recording carrier (hereinafter simply referred to as a disc) such as a video disc into a desired shape, the conventional method is to mold a LP record, etc.
method, an injection method in which semi-molten resin is pressure-injected from a nozzle into a closed space formed by upper and lower molds, and a flat pressure press method when molding Sonosheet.

All of these methods require a long molding time (for example, 30 seconds for a P record) because they are molded into a desired shape by thermal recycling, and have the drawbacks of shrinkage distortion caused by heat.

In addition, in the case of Sonosheet, the stamper is heated in advance with a heater etc. so that it becomes soft (and is constantly cooled).
Although it has the advantage of short molding time, it is not suitable for molding faithful signals, and of course it is not used for manufacturing high-density information media such as video discs. I can't.

In addition, a molding method different from the above three methods has been attracting attention in recent years. This method molds signals by irradiating ultraviolet rays onto the surface of an ultraviolet-curable resin and hardening the resin. Using this method, it is possible to create a disc that is faithful to the signal in an extremely short molding time. Although this is possible, it has the disadvantage that the ultraviolet curable resin shrinks when it cures, causing distortion due to the shrinkage.

As a result of various studies in view of the above points, the inventors of the present invention have found the following solution.

In other words, it is an unavoidable phenomenon that a single UV-curable resin will shrink during curing, but by placing the resin on a base material and keeping the thickness of this resin below a certain value, the base material can be reduced. The material functions to prevent distortion due to shrinkage without succumbing to the shrinkage stress of the resin.

The present invention was made based on such a viewpoint,
The present invention will be explained in detail below based on one embodiment. The drawing is an explanatory diagram of an apparatus for carrying out the method of the present invention.

A disk base material (4) made of a material that transmits ultraviolet rays is placed on a lower mold (5) that is also made of a material that transmits ultraviolet rays, and a dispenser (ultraviolet curing by force) is placed in the center of the surface of this disk base material (4). Drop mold resin (3). After this, the dispenser (the tip of the force immediately escapes from the press part to the outside, and the stamper (2) attached to the upper mold (1) descends from above. At this time, UV curing resin (
3) is placed on the base material (4) like a mirror cake, so the stamper (2) first comes into contact with the ultraviolet curable resin (3) at a point, and then the stamper (2) is lowered further. (By applying pressure to the ultraviolet curable resin), the contact area expands in an annular shape from the point, and at the same time, the ultraviolet curable resin (3) gradually spreads to the surrounding area and is sufficiently spread over the base material (4). At this point, the signal can be molded into the ultraviolet curable resin by maintaining that state and curing it by irradiating it with ultraviolet rays from an ultraviolet light source (6).

Here, resins such as vinyl chloride, acrylic, polypropylene, polyester, ABS, urethane, polyethylene, and nylon can be used as the disk base material (4), and ultraviolet-transparent glass can be used as the lower mold (5). A mercury lamp can be used as the ultraviolet light source (6).

As described above, the ultraviolet curable resin (3) shrinks and becomes distorted upon curing. By suppressing the stress of this shrinkage to below the rigidity of the base material (41), specifically by suppressing the thickness of the ultraviolet curable resin (3) relative to the thickness of the base material (4) to below a certain value, the Distortion can be prevented, but on the other hand,
Since the thickness of the ultraviolet curable resin is controlled by pressing, the pressure to be applied and the viscosity of the ultraviolet curable resin must also be considered.

That is, first of all, let's look at the viscosity of the UV-curable resin (3). If the viscosity is too low, the UV-curable resin (3) will flow immediately after being dropped onto the base material (4), resulting in the shape of the kagami-mochi being distorted. Therefore, it is not possible to gradually spread the UV resin (3) as described above, and air bubbles will be mixed in.

In addition, if the viscosity is too high, the base material (4) will change from a kagami-mochi shape to
In order to spread the pressure all over the top, an extremely large amount of pressure is required, which is impractical in terms of equipment lifespan and mass productivity (and it is extremely difficult to maintain a uniform disk thickness at all times). be.

From this viewpoint, the correlation between the thickness and viscosity of the ultraviolet curable resin (3) to be applied to the base material (4) and the pressure to be applied was confirmed in an experiment (2), and the results are shown below.

In addition, here, the pressurization time (3 seconds) and temperature (room temperature) were fixed, but considering mass production, it is preferable that the pressurization time is within 1.5 seconds, and the temperature also varies during actual work. This is taken into consideration.

50. 2 0.6 -
Air bubbles 10040 Distortion 4 30
5 l 2B No distortion l
100 6 No distortion 200
4, #, 40
Distortion occurrence #-5-55 #' 10 25
No distortion 010 500' 5 45
Distortion occurred 10'#, 50 3020 No distortion 015 700 - 50 45
Distortion occurred 5028 No distortion 1000 10 80
Strain generation 30〃60 #100 #30 As is clear from this experimental result, in order to form the ultraviolet curable resin (3) into a kagami-mochi shape without air bubbles, the viscosity must be at least 100 C.p. It is understood that this is necessary.

Furthermore, ultraviolet-transmitting glass is mainly used as the lower mold (5) of manufacturing equipment, and the maximum stress σmax when a concentrated load is applied to such a lower mold (5) is determined by the following formula. .

σma-x-β×d (β: coefficient, P: load, thickness of T-glass) Applying this formula, if the thickness of the glass is 511II+, the maximum stress is about 50Kg/1lII! In fact, it is preferable that the thickness of the glass is about 5 days due to the problem of ultraviolet transmittance.

In view of this and the above experimental results, it is desirable that the viscosity of the ultraviolet curable resin be 700 C.P or less.

From the point of view of the pressure that should be applied, it is 5 to 50 kg/C.
It is understood that the upper die (11) and the lower die (5) should be crimped together with a pressure within the range of 1d.

And also, the thickness of the base material (4) is Q, 6flllll
If it is +, the thickness of the ultraviolet curable resin (3) is 30 μm.
m or less.

Preferably, if the thickness is kept to 10 μm or less, distortion will not occur, and if the thickness of the base material (4) is 1 mm, the thickness of the ultraviolet curable resin (4) should be kept to 40 μm or less to prevent the occurrence of distortion. In view of this, there is a correlation between the thickness of the base material (4) and the thickness of the ultraviolet curable resin (3) in terms of strain generation, and the thickness of the ultraviolet curable resin (3) is the same as that of the base material (3).
1/ of the thickness of 4)! If it is less than 1/60, preferably less than 1/60, a disk without distortion can be manufactured.

As described above, according to the present invention, when manufacturing a disk using an ultraviolet curable resin that enables good molding in a short time, It is possible to prevent the occurrence of distortion, and it is possible to manufacture disks with extremely high precision.

BRIEF DESCRIPTION OF THE DRAWINGS The drawing is an explanatory diagram showing an example of an apparatus for carrying out the method of the present invention. A1)...Top mold (2)...Stambar (3)...
・Ultraviolet curing resin (4)・-・Disc base material (5
)... Lower mold (6)... Ultraviolet light source (Power... Dispenser patent applicant Toppan Printing Co., Ltd. Representative Kazuo Suzuki 6

Claims (1)

[Claims] 1) A method for producing a high-density information recording carrier using an ultraviolet curable resin having a viscosity of 100 C.p. ~700 C, p, ultraviolet curable resin was placed on the base material in a kagami-mochi shape, and a stamper was applied to this resin at 5 Kt, #ld~
50 to 9/c++f pressure to press and mold the resin while sequentially expanding it into an annular shape from point or line contact, and finally reduce the thickness of the resin to 1/60 or less of the thickness of the base material, preferably 1/60.
A method of manufacturing a high-density information recording carrier by following the steps below and then curing the resin by irradiating it with ultraviolet rays.