JPH03241545A - Production of optical recording medium - Google Patents

Abstract

PURPOSE:To prevent the inclusion of bubbles, etc., by forming parts exposed with a resin in the outer and inner peripheral parts of substrates and subjecting the exposed resin parts to a heating treatment for 10 seconds to 10 minutes at 70 to 140 deg.C, then applying an adhesive thereto. CONSTITUTION:The parts exposed with the resin are formed in the outer and inner peripheral parts of the resin substrates on the side provided with the recording layers. The exposed resin parts are subjected to the heating treatment for 10 seconds to 10 minutes at 70 to 140 deg.C, more preferably 80 to 130 deg.C and the adhesive is applied thereon. The exposed parts are thus adhered. Since the adhesive has the viscosity as high as 100 to 5,000 poises at 20 deg.C viscosity and, therefore, bubbles are often intruded into the adhesive. The adhesive is preferably used after the adhesive is subjected to vacuum defoaming prior to application at the time of use. The coating is executed by a method for setting an adhesive discharge nozzle in a specified radial position to one of the stuck substrate surfaces and applying and forming the adhesive to a doughnut shape so as not to generate the bubbles on the circumference, while rotating the substrate, then superposing the other substrate on the coated substrate and sticking the substrates to each other. The extremely stable and good optical recording medium is obtd. in this way.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method of manufacturing an optical recording medium, and in particular, to a method of manufacturing an optical recording medium, in which an optical recording medium is manufactured by forming a recording layer on a transparent resin substrate using an adhesive. This invention relates to an improvement in a method of laminating an optical recording medium.

[Prior art and its problems] Optical recording media for optical video discs, optical audio discs, and writable discs are basically those in which a metal recording layer, a dye recording layer, etc. are provided on a plastic substrate. Known types include a perforation type that uses melting of a film with a light beam and sublimation, a type that uses phase transition between crystal and amorphous, and a magneto-optical type that uses magneto-optic effects. In either type, the recording layer is usually formed on a light-transmissive substrate along with other auxiliary layers, etc., and then bonded with these layers inside to prevent dust from adhering to the recording layer and forming scratches. The structure is such that they are bonded together using a chemical agent, and recording and playback is performed through the substrate. In this case, as the adhesive, a hot melt adhesive is often used because it is solvent-free, has no adverse effect on the recording layer, and has a simple working process.

In the case of hot melt adhesives, it is relatively easy to incorporate them into automated processes because they can be applied directly to the adherend.
Since it must be thermally melted, if the melting temperature is high, the adherend may be damaged by the heat, and if the melting temperature is lowered, the viscosity increases, making it difficult to coat or making the coated layer thicker.

Other known adhesives include two-part epoxy adhesives and urethane adhesives, but two-part epoxy and urethane adhesives require operations to weigh and mix the two parts. During the bonding process, air bubbles and moisture contained in the adhesive layer often deteriorate the magnetic properties of the recording layer. In addition, the inclusion or entrainment of air bubbles will significantly affect weather resistance.
At high temperatures, cracks occur in the recording layer starting from the air bubbles, causing bit errors during recording or reproduction of the medium.

1 Means for Solving the Problem 1 The present invention is characterized in that a recording medium having at least a recording layer on a substrate is placed facing each other, or a substrate having the recording layer and another substrate without a recording layer are placed facing each other. An object of the present invention is to provide an adhesion method that does not cause problems such as strength and deterioration over time when bonding a substrate having a structure with an adhesive.

The gist of the present invention is that resin substrates provided with a recording layer,
Or, when bonding the substrate and another substrate with an adhesive with the recording layer side inside, the resin may be exposed on the outer and inner peripheries of the resin substrate on the side where the recording layer is provided. A method for producing an optical recording medium, comprising: forming a resin-exposed portion, heat-treating the exposed resin portion for 10 seconds to 10 minutes at a temperature of 70 to 140°C, and then applying adhesive to perform adhesion. .

The substrate forming the recording medium is made of resin such as polycarbonate or polymethyl methacrylate.

Adhesives that can be suitably used in the present invention include solvent-free adhesives, such as one-component or two-component epoxy adhesives, or moisture-curable or two-component urethane adhesives. These are suitable adhesives because they are inert to the recording film.

However, this type of adhesive usually has a viscosity of 100°C at 20°C.
Since it has a high viscosity of ~5,000 poise, air bubbles are often mixed into the adhesive, so it is preferable to vacuum defoam before application.

In the coating method, an adhesive discharge nozzle is set at a fixed radius position on one side of the bonded substrate surface, and the adhesive is coated on the circumference in a doughnut-shape while rotating the substrate to avoid generating air bubbles. The coated substrate may be laminated with the other substrate.

When bonding is performed, the adhesive spreads in the radial direction on the inner and outer circumferential sides of the substrate, and finally reaches the entire area of the substrate. In this case, it is best to optimize the adhesive application amount and application position so that the adhesive does not protrude from the inner and outer peripheral sides.

As the magneto-optical recording layer, a layer structure generally used as a known magneto-optical recording layer is used. For example, TbFe,
Amorphous magnetic alloys of rare earths and transition metals such as TbFeCo, TbCo, DyFeCo, MnB1. MnCu
A polycrystalline perpendicular magnetization film such as B1 is used.

A single layer may be used as the magneto-optical recording layer, and TbxF
Two or more recording layers may be stacked, such as eCo/Tb or FeCo. (x<y) An interference layer can also be provided between the substrate and the recording layer.

This layer utilizes the optical interference effect of a transparent film with a high refractive index.
This is to reduce noise and improve the C/N ratio by lowering the reflectance. The interference layer is made of metal (AI-
0, Ta-0, Al-Ta-0 composite oxides, etc.), metal nitrides (e.g. 5i-N, Al-N, Ge-N, etc.)
is used.

It is desirable to provide a dielectric layer selected from the same material as the interference layer on the surface of the recording layer opposite to the interference layer.

The recording layer, interference layer, dielectric layer, etc. are to be formed at a portion excluding the outer and inner circumferential portions of the substrate, and at least exposed portions of the substrate resin are formed at the outer and inner circumferential portions of the substrate. , it is necessary to obtain adhesive strength at this part. Of course, the same applies to the other substrate to be bonded to this one.

In the present invention, the coated surface is heat-treated before the adhesive is coated.

The degree of treatment is 10 seconds to 10 seconds at a temperature of 70 to 140'C.
for 10 seconds to 10 minutes, preferably at a temperature of 80 to 130°C.
It takes about a minute.

This heating improves the affinity of the surface of the exposed part of the resin substrate, and also prevents water adhering to the surface from flying away and entraining air bubbles when applying the adhesive, and from generating air bubbles later. it is conceivable that.

[Examples] Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded.

Examples 1 to 5, Comparative Example 1 Thickness 1.2 mm, diameter 130 mmφ, center hole 15 mmφ
SiN/TbxFeCo on Bocker Bonate substrate
/TbyFeCo/5iN (x<y) was formed by sputtering. During sputtering, polycarbonate is exposed on the outer and inner peripheries of the substrate by covering the outer and inner peripheries of the substrate. 62 mm from the position) The side on which the recording layer of this substrate was provided and the adhesive side of the bocker carbonate substrate on which the recording layer was not provided were heated at 8000 for 10 minutes and at 100.
It was heated at 120°C for 30 seconds and 20 seconds at 120°C.

These substrates are paired as one with a recording layer and one without, and a two-component epoxy adhesive (defoamed with a vacuum pump) is applied to one disk (with a recording layer). After coating, another disc (without a recording layer) was gently placed on it and bonded together.

After bonding, it was cured at room temperature for 24 hours.

The inspection was carried out visually, and the presence or absence of defects (bubbles, etc.) was confirmed by inspecting the disc from the side of the disc that had no recording layer under bright lighting. According to this test, the number.

The presence or absence of air bubbles on the order of .

When the product yield was calculated using disks with confirmed defects as defective products and disks with no confirmed defects as products, the yield was over 95% for all irradiation doses, even though heat treatment was performed.

On the other hand, in the case of disks that were not heat-treated, the yield was 40%.

[Effects of the Invention] According to the method of the present invention, when assembling an optical recording medium using an adhesive, defects due to entrapment of air bubbles can be prevented, and optical recording media of excellent quality can be produced in an extremely stable manner. be able to.

Claims (1)

[Claims] (1) When bonding resin substrates provided with a recording layer to each other or to another substrate with the recording layer side inside using an adhesive, the resin on the side provided with the recording layer Exposed parts of the resin are formed on the outer and inner parts of the manufactured substrate, and the resin exposed parts are heated for 10 seconds at a temperature of 70 to 140°C.
1. A method for producing an optical recording medium, which comprises performing a heat treatment for 10 minutes and then applying an adhesive to perform adhesion.