JPH0554185B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Technical Field> The present invention relates to an optical memory element that records, reproduces, erases, etc. information using light such as a laser.

<Prior Art> In recent years, research and development of optical memory devices has been actively conducted amid increasing demand for storage devices capable of large capacity, high density, and high-speed access.

In an optical memory element, an optical recording member layer is formed on a disk-shaped support base made of synthetic resin such as glass or acrylic resin. It is common to attach them so that they face each other, so that they can be used on both sides. In addition, for single-sided recording, there are cases in which a support base on which an optical recording member layer is formed and a support base on which no optical recording member layer is formed are bonded together so that the optical recording member layer is sandwiched between the two support bases. . In either case, in order to avoid oxidative corrosion of the optical recording member layer from the peripheral edge exposed to the outside air, it is necessary to provide a recording member layer missing portion in which the optical recording member layer is not formed in the peripheral edge.

By the way, two methods are widely known for bonding two support substrates together. One is a method in which the above-mentioned recording member layers are bonded together via a spacer in the missing portion, and the space between the two supporting substrates is filled with an inert gas or the like (air sandwich structure). However, with this method, the bonding process becomes complicated, and in order to ensure mechanical strength after bonding, the adhesive area must be secured to a certain extent, so the pre-storage capacity of the optical memory element must be increased. There is a disadvantage that the amount decreases.

Another method is to bond the entire surface of the supporting substrate with an adhesive, and this method can avoid the above problem. In this case, UV-curable adhesives are widely used as adhesives because they are one-component, have a long open time (time from adhesive application to bonding), and are advantageous in terms of workability. but,
Since the optical recording layer, which is mainly made of metal, is difficult to transmit ultraviolet rays, the optical recording layer cannot be formed on one of the supporting substrates, and therefore an optical memory element that can be used on both sides cannot be realized.

In addition, many of the materials that make up the optical recording layer of optical memory devices have properties that deteriorate due to oxidation, and corrosion tends to progress rapidly in the presence of moisture, so it is important to improve the moisture resistance of the device. has become an unavoidable problem for practical application. However, with the above-mentioned sealing technology based on conventional adhesives, under storage environments such as high temperature and high humidity, the adhesive itself absorbs moisture, swells, peels from the substrate, and deteriorates in adhesion. However, the problem of accelerating moisture intrusion through the interface and triggering corrosion of the optical recording member layer cannot be avoided.

<Purpose> The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to cure two supporting substrates each having an optical recording member layer formed in the main area by either ultraviolet curing or anaerobic curing. The aim is to provide an optical memory element that can be used on both sides with a simple bonding process by bonding with a curable adhesive.In addition, by adding an adhesion agent to the adhesive, it has excellent moisture resistance. Achieving a new optical memory device.

<Structure> The present invention provides an optical memory element in which two supporting substrates each having an optical recording member layer formed in a main region are bonded together with an adhesive so that the optical recording member layers face each other. As such, it uses an adhesive that undergoes a curing reaction in both ultraviolet curable and anaerobic curable types, and in order to improve moisture resistance, a water-repellent silane coupling agent or titanium coupling agent is used. This adhesive uses an adhesion-imparting agent such as

The optical recording member layer targeted by the present invention includes a Te thin film,
It is a medium that is easily corroded by air or moisture, such as Te lower oxide thin films, dye thin films, rare earth-transition metal alloy amorphous thin films, etc. Rare earth-transition metal alloy amorphous thin films are shown in Examples later.
In addition to GdTbFe thin films, there are also TbDyFe thin films. An optical memory element constructed using these optical recording member layers has a structure in which an optical memory medium is sandwiched between two substrates bonded together.

The adhesive used in the present invention can be cured by either ultraviolet curing or anaerobic curing as described above, and specific examples of its components are as follows.

As the base acrylic urethane oligomer, polyester urethane methacrylate, polyether urethane methacrylate, polybutadiene urethane methacrylate, etc. are used.

More specifically, polyester urethane methacrylate includes ethylene glycol, diethylene glycol, 1,4-butanediol, 1,6
- A polyester polyol having a hydroxyl value of 20 to 200, which is composed of a polyol such as hexanediol or neopentyl glycol and a polycarboxylic acid such as adipic acid, fumaric acid, phthalic acid, or terephthalic acid, and a polyisocyanate such as 1, At least one of 6-hexamethylene diisocyanate, methylene-bis-(4-phenyl isocyanate), and tolylene diisocyanate is reacted with one polyisocyanate per hydroxyl group of a polyester polyol, and the remaining polyisocyanate is further reacted with one polyisocyanate. It is obtained by reacting one isocyanate group with at least one methacrylate containing a hydroxyl group, such as 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, etc., and polyether urethane methacrylate is obtained by reacting polyethylene glycol, polypropylene glycol, From hydroxyl value 20 such as polytetramethylene ether glycol
Hydroxyl group of polyether polyol with 200 1
react with one of the above-mentioned polyisocyanates,
Polybutadiene methacrylate is obtained by reacting one isocyanate group remaining in polyisocyanate with the above-mentioned hydroxyl group-containing methacrylate. It is obtained by reacting one hydroxyl group of polybutadiene having a molecular weight of 200 to 200 with one of the above-mentioned polyisocyanates, and further reacting one of the above-mentioned hydroxyl group-containing methacrylates with one isocyanate group remaining in the polyisocyanate. 30 to 80 parts of the above acrylic urethane oligomer, at least one hydroxyalkyl methacrylate such as 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, etc. as a cut monomer that lowers the viscosity of the adhesive and improves surface workability, and an alkyl urethane oligomer. At least one methacrylate such as 2-ethylhexyl methacrylate, lauryl methacrylate, tridecyl methacrylate, etc.
20 to 70 parts of seeds, and at least one of dimethylbenzyl ketal, benzoin ethyl ether, benzoin isopropyl ether, benzophenone, benzyl, etc. as a photosensitizer.
0.1 to 10 parts, preferably 1 to 3 parts of seeds;
Further, as an anaerobic agent, 0.1 to 3 parts of at least one hydroperoxide such as 1,1,3,3-tetramethylbutyl hydroperoxide, cumene hydroperoxide, tert-butyl hydroperoxide, etc. is added. and 0.01 to 1 part of at least one tertiary amine such as N,N-dimethylaniline, N,N-dimethyl-P-toluidine, etc., and storage stabilizers such as hydroquinone, methoquinone,
At least one of ditertiary butyl-P-cresol and the like is added in an amount of 0.01 part to 0.5 part. Furthermore, as an additive for improving adhesion, which is another feature of the present invention, at least one of a water-repellent silane coupling agent or a titanium coupling agent is added to the adhesive in an amount of 0.5 to 10 parts, preferably 2 parts. Use parts 1 to 5. Silane coupling agents include vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, etc., and titanium coupling agents include diisopropoxybis(acetylacetonato)titanium, Examples include dihydroxybislactatotitanium.

By using this adhesive, it is possible to realize an optical memory element that is easy to bond and can be used on both sides. In addition, the addition of an adhesion agent eliminates problems such as moisture absorption, swelling, and peeling of the adhesive portion, and the moisture resistance of the optical memory element itself is greatly improved.

<Example> Hereinafter, an example of the optical memory device according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is an external perspective view of an optical disk as an example of an optical memory element according to the present invention, and FIG. 2 is a side sectional view of the main part thereof. 1 is a support base made of glass or synthetic resin such as acrylic resin, 2 is an optical recording member layer, 3 is an adhesive, 4 is a center hole, and 5 is a recording member layer missing portion where the optical recording member layer 2 is removed. .

After forming the optical recording member layer 2 on the surfaces of the two support substrates 1 and applying the adhesive 3 to the entire surface having the optical recording member layer 2, the two support substrates 1 are attached to the optical recording member layer 2. They are pasted together so that they face each other, and ultraviolet rays are irradiated from one side of the support base 1 to bond the recording member layer missing portion 5 with ultraviolet curing, and the adhesive 3 between the optical recording member layers 2 is anaerobic curable. Glue.

In this way, an optical memory element that can be used on both sides can be realized through a simple bonding process. Furthermore, here, the effect of improving reliability by adding an adhesion agent will be illustrated by taking as an example a magneto-optical memory element that enables additional recording and erasing of information.

The magneto-optical memory element has a laminated structure in which an amorphous GdTbFe memory thin film, an AlN dielectric film, and an SUS reflective film are successively sputtered on a glass substrate, with the film surfaces facing each other. The structure is bonded together with adhesive. In particular, the GdTbFe film layer is susceptible to oxidative corrosion, and a reliable sealing bonding method is desired for this type of memory element. In this example as well, the recording portion missing portion described above is provided at the periphery of the element.

Here, the memory elements using various adhesives were prepared and subjected to a humidity resistance test. The environmental test conditions include temperature and humidity cycle tests (-20℃ and 70℃, 95%
RH cycle is repeated at a rate of 4 cycles per day), constant temperature and humidity test (60℃, 95%RH)
and a hot water immersion test (80°C warm water).

The anaerobic UV-curable adhesive is made of polyester urethane methacrylate 55 as a base prepared by reacting a polyester polyol with a hydroxyl value of 110 containing ethylene glycol and adipic acid with isophorone diisocyanate and hydroxyethyl methacrylate in the proportions described above.
25 parts of hydroxypropyl methacrylate and 20 parts of 2-ethylhexyl methacrylate were added as cutting monomers, and further 0.1 part of N,N-dimethyl-P-toluidine and 0.4 part of cumene hydroperoxide were added as anaerobic agents, and benzyl dimethyl A mixture prepared by adding 2 parts of ketal as a photosensitizer and 0.02 part of hydroquinone as a storage stabilizer was used. The anaerobically imparting ultraviolet curing adhesive containing the adhesion imparting agent according to the present invention was prepared by adding 4 parts of γ-methacryloxypropyltrimethoxysilane as an adhesion imparting agent to the above adhesive composition.

As a result of comparing the environmental test results of memory elements using these adhesives, it was found that in the former, wrinkle-like peeling, which was thought to be caused by swelling, was observed on the adhesive surface after about one week of cycle tests and constant temperature and humidity tests. On the other hand, no abnormality was observed in the latter case even after 3 weeks. In addition, in a hot water immersion test, it was found that the time it took for the former to become visible before peeling was within 5 hours for the former, while for the latter it was over 25 hours. Furthermore, when comparing the tensile bond strengths of the adhesives, both have bond strengths of 60Kg/cm2 or ^more before the hot water immersion test (60℃, 10 hours), but after the hot water immersion test, the former The latter exhibited a tensile bond strength of 44 Kg/cm ² while only 8 Kg/cm ² .

It can be seen from the above examples that the moisture resistance of the memory element is definitely improved.

<Effects> As explained above, since an adhesive that can be cured by both ultraviolet rays and anaerobic curing is used for bonding the supporting substrates, it is possible to easily realize an optical memory element that can be used on both sides, and By adding an adhesion agent to the adhesive, the adhesion of the adhesive part is maintained over a long period of time, eliminating problems such as moisture absorption, swelling, and peeling, and improving the reliability of the device itself.

[Brief explanation of the drawing]

FIG. 1 is an external perspective view showing a disk as an embodiment of the optical memory device according to the present invention, and FIG.
FIG. 3 is a side cross-sectional view showing the main part of the figure. 1...Supporting base made of glass or synthetic resin,
2... Optical recording member layer, 3... Adhesive, 4... Center hole, 5... Recording member layer missing portion.

Claims (1)

[Scope of Claims] 1. An optical recording member layer through which ultraviolet rays are difficult to pass is formed in the main region of each of two light-transmissive supporting substrates, and the two optical recording member layers are arranged so that the optical recording member layers face each other. In the method for producing an optical memory element in which two supporting substrates are bonded together with an adhesive, the two supporting substrates are bonded together using an adhesive that contains in advance a component that imparts ultraviolet curability and a component that imparts anaerobic curability. bonding and irradiating the bonded two supporting substrates with ultraviolet rays to cure the adhesive in areas where the optical recording member layers do not face each other;
A method for producing an optical memory element, characterized in that the adhesive in the area where the optical recording member layers face each other is cured by cutting off contact with air. 2. The method for producing an optical memory element according to claim 1, wherein at least one of a silane coupling agent and a titanium coupling agent is added to the adhesive in order to improve adhesion during bonding. 3. A method for producing an optical memory element according to claim 1 or 2, wherein the optical recording member layer is a rare earth-transition metal alloy thin film.