JPH01298546A - Optical information recording medium - Google Patents

Abstract

PURPOSE:To prevent the deterioration of a recording layer by UV rays by providing a UV absorptive layer between a transparent resin substrate and a protective layer consisting of a UV curing type resin. CONSTITUTION:This optical information recording medium is constituted by providing the recording layer 2 which allows recording by a laser beam on the grooved surface for tracking of the transparent resin substrate 1 having the tracking grooves 6, sticking the recording layer 2 and a protective substrate 4 via an adhesive agent 3, and providing the protective layer 5 which protects the surface of the substrate 1 via the UV absorptive layer on the surface of the substrate 1. The UV curing type resin is used for the protective layer 5. Said resin is more particularly preferably acrylic resins such as epoxy acrylate and urethane acrylate. The UV absorptive layer 7 is exemplified by a salicylic acid system, benzophenone system, benzotriazole system, cyanoacrylate system, etc. The deterioration of the recording layer by UV rays is prevented in this way.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an optical information recording medium.

[Prior Art] Conventionally, magnetic materials have been mainly used as recording materials embedded in cards such as credit cards, bank cards, and clinic carts.

Although such magnetic materials have the advantage that information can be easily written and read, they have problems such as the content of the information changing easily and high-density recording being impossible. In order to solve this problem, optical information recording media such as rice cards have been proposed as a means for efficiently handling a wide variety of information.

Optical information recording media, including optical carts, generally use laser light to evaporate part of the recording layer, change its reflectance, or deform it to record information. Information is reproduced by the difference in optical reflectance or transmittance caused by the difference in optical reflectance or transmittance. In this case, the recording layer does not require any development processing after information is written, and can be read directly after writing, which is what is called DRAW (Direct read after write).
e) It is effective as a recording medium because it is capable of high-density recording and additional writing is possible.

Although there are metal materials and organic dye-based materials as recording media, organic dye materials are generally used because of their ease of handling and low cost.

FIG. 2 is a schematic cross-sectional view of a conventional optical information recording medium.

In the figure, 1 is a transparent resin substrate, 2 is a recording layer, 3 is an adhesive, 4 is a protective substrate, 6 is a tracking groove, and 5 is a protective layer. In FIG. 2, information is recorded and read by optically writing and reading information through a transparent resin substrate l and a tracking groove 6, and by using the fine irregularities of the tracking groove 6 to create a phase difference between laser beams. Tracking is performed by

In such conventional optical information recording media, plastic substrates are used as transparent resin substrates, which are inexpensive and can be mass-produced because of their large capacity and personal use.

However, plastic substrates are prone to scratches on the surface during handling, and during recording and reproduction, the AT is likely to come off, and the contrast of recorded signals becomes low, leading to increased reading errors. Therefore, in order to prevent these scratches, a protective layer, a so-called hard coat layer, is provided to protect the plastic substrate. As the material for the eight coat layer, an ultraviolet curable resin is used, which requires a short working time and has excellent productivity.

[Problem 8 to be solved by the invention] However, in conventional optical information recording media such as optical cards as described above, when providing a protective layer made of an ultraviolet curable resin on a transparent resin substrate, ultraviolet m irradiation is required. As a result, the organic dye-based material that is the recording material of the recording layer deteriorates due to ultraviolet rays, resulting in a decrease in reflectance, which adversely affects the recording and reproducing characteristics of the optical information recording medium, making recording and reproducing impossible. .

Another drawback is that the organic dye-based material deteriorates when the optical information recording medium is exposed to direct sunlight or the like during normal use.

The present invention was made to improve the drawbacks of such conventional optical information recording media, and by providing an ultraviolet absorbing layer between the surface of a transparent resin substrate and a protective layer made of an ultraviolet curable resin. An object of the present invention is to provide an optical information recording medium whose recording layer does not deteriorate even if it is irradiated with ultraviolet rays when forming a protective layer or exposed to direct sunlight during normal use.

[Means for Solving the Problems] That is, the present invention provides an optical information recording medium having a resin substrate, a recording layer, and a protective substrate, in which a protective layer made of an ultraviolet curable resin is provided on the surface of the resin substrate via an ultraviolet absorbing layer. An optical information recording medium is characterized in that it is provided with:

Hereinafter, the present invention will be explained based on the drawings.

FIG. 1 is a sectional view showing a typical embodiment of the optical information recording medium of the present invention. In FIG. 1, the optical information recording medium of the present invention is provided with a recording layer 2 that can be recorded by a laser beam on the tracking groove surface of a transparent resin substrate l having a tracking lI6, and the recording layer 2 and the protective The transparent resin substrate l is bonded to the substrate 4 via the adhesive 3.
A protective layer 5 for protecting the surface of the transparent resin plate 1 is provided on the surface of the transparent resin plate 1 with an ultraviolet absorbing layer 7 interposed therebetween.

As the transparent resin substrate 1, a plastic substrate transparent to the laser beam is used, and examples thereof include polymethyl methacrylate, polycarbonate, polyvinyl chloride, and the like.

The storage substrate 4 is not particularly limited, and may be a transparent resin substrate.
It may be made of a similar material, but it does not necessarily have to be transparent.

The adhesive 3 is not particularly limited, but a thermoplastic adhesive, particularly a hot melt type adhesive, is usually preferred because of its ease of use.

The recording layer 2 is made of an organic dye-based material, such as polymethine-based, azo-based, or cyanine-based dyes.

For the protective layer 5, an ultraviolet curable resin is used, and acrylic resins such as epoxy acrylate and urethane acrylate are particularly preferred.

In the present invention, the ultraviolet absorbing layer 7 can be made of salicylic acid, benzophenone, benzotriazole, cyanoacrylate, etc., and these can be used alone or in a state where they are added to a polymer such as acrylic.

[Function] The optical information recording medium of the present invention is an optical information recording medium in which a recording layer is provided on a transparent resin substrate, and the recording layer and a protective substrate are bonded together via an adhesive. By providing an ultraviolet absorbing layer between a protective layer made of an ultraviolet curable resin, the ultraviolet absorbing layer is provided even if the protective layer is irradiated with ultraviolet rays when curing the protective layer. UV deterioration of the recording layer can be prevented.

[Example] Hereinafter, the present invention will be described in detail based on Examples.

Example 1 A cart-sized transparent resin substrate (width 85.5 mm,
As a recording layer, a polymethine dye consisting of the following structural formula CI) was formed to a film thickness of 0.1 #Ls by a C1'04° (1) spin-coding method. A 0.05 m thick thermoplastic adhesive made of card-sized ethylene-vinyl acetate copolymer is interposed thereon.
Protective substrates made of 3.5 - polymethyl methacrylate were superimposed and laminated. Next, phenyl salicylate was applied to the surface of the transparent resin substrate to a thickness of 0.1 μm using a spin coater or a roll coater to form an ultraviolet absorbing layer.

Thereafter, an ultraviolet curable resin made of urethane acrylate resin is applied onto this ultraviolet absorbing layer to a thickness of 5 mm using a spin coater or a roll coater.
Illuminance 80W/cm, irradiation distance fi15+1, time 10 seconds)
It was irradiated with ultraviolet light and cured.

The reflectance of the thus obtained optical information recording medium was measured using a reflectance measuring device, and the result was 14%, indicating that good recording and reproducing characteristics were obtained.

Comparative Example 1 An optical information recording medium was produced in the same manner as in Example 1 except that no ultraviolet absorbing layer was provided. The reflectance of the obtained optical information recording medium was measured in the same manner as in Example 1. As a result, the reflectance was reduced to 10%, and recording and reproduction could not be performed.

[Effects of the Invention] As explained above, the optical information recording medium of the present invention can be protected by irradiation with ultraviolet rays by providing an ultraviolet absorbing layer between a transparent resin substrate and a protective layer made of an ultraviolet curable resin. When curing the layer, it is possible to prevent the recording layer from being deteriorated by ultraviolet rays, and it is also possible to prevent the recording layer from deteriorating when the optical information recording medium is exposed to direct sunlight during normal use.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the optical information recording medium of the present invention, and FIG. 2 is a schematic sectional view of a conventional optical information recording medium. l... Transparent resin substrate 2... Recording layer 3... Adhesive 4... Protective substrate 5... Protective layer
6... Tracking groove 7... Ultraviolet absorbing layer Fig. 1 6 Track 1 Socking groove Fig. 2

Claims (1)

[Claims] An optical information recording medium comprising a resin substrate, a recording layer and a protective substrate, characterized in that a protective layer made of an ultraviolet curable resin is provided on the surface of the resin substrate via an ultraviolet absorbing layer.