Dainippon Ink and Chemicals, Incorporated

Kazuo Murakami

Hiroshi Fukutomi

Shoei Ebisawa

Takashi Kitsunai

Koichi Fujii

An optical disk comprising a first substrate, a first reflective layer for reflecting laser beams for information reading formed on the first substrate, and a resin layer made of a cured film of an ultraviolet curable composition formed on the first reflective layer, wherein the first reflective layer is a reflective layer made of silver or an alloy containing silver as a main component, and the ultraviolet curable composition contains (a) a radical polymerizable compound, (b) a compound represented by the following formula (1) and (c) a radical photopolymerization initiator. 

Optical disk

An object is to provide a technique of imparting durability which is equal to that of existing types of DVD-5 and DVD-10 as well as DVD-9 using gold or a silicon based compound as a semitransparent film, to a DVD obtained by bonding two substrates having information recording layers, respectively, on each outermost layer of which a thin film of silver or an alloy composed primarily of silver is formed. Using an optical disc wherein ratios of error rates before and after an environmental test at 80&deg; C. and 85% RH for 96 hours is 10 or less, and an ultraviolet curable composition for optical disc wherein a water absorption rate of the cured coating film is 2.0 wt % or less and a water-vapor permeability at a film thickness of 50 &mgr;m is 70 g/m &middot;day or less, the object described above is achieved.

Optical disk and ultraviolet-curing composition for optical disk

In order to provide an adhesive composition which can bond a substrate having a reflecting layer made of a silicon compound to which adhesion of conventional ultraviolet curable compositions is insufficient, an ultraviolet curable composition is provided which comprises: a silane coupling agent containing an epoxysilane or a (meth)acrylsilane; an ultraviolet curable compound; and a photopolymerization initiator.

Optical disc and process for producing optical disc

To obtain a digital video disc having excellent durability in a high temperature and high humidity environment, an ultraviolet curable composition prepared such that water in which the cured coating film has been immersed has a specific conductivity of 100 &mgr;S/cm or less is provided as an adhesive for use in bonding two discs with information recording layers, respectively, having thin films of different kinds of material.

Ultraviolet-curing composition, optical disk, and method of producing optical disk

The present invention relates to a method for bonding together two disc substrates, at least one disc substrate having a UV transmissive-visible light reflective information recording layer provided on a UV transmission base. In this method, the disc substrates are bonded together, so that the information recording layer of one disc substrate faces the other disc substrate, by employing UV irradiation to cure a UV curable composition used as a bonding agent. In the case of the present invention, to cure the bonding agent, UV is irradiated in a single or repeating flash so as not to impair the information recording layer. As a result, the bonding agent can be cured in a shorter period of time with less energy consumed as compared to the conventional method of using conditions irradiation of UV light to cure a UV curable composition used as a bonding agent. Accordingly, the present method enables a product disc to be obtained in a shorter time, with less energy used, so that productivity (i.e., number of bondings per unit time) is improved.

Disc bonding method

The present invention relates to a method for bonding together two disc substrates, at least one disc substrate having a UV transmissive-visible light reflective information recording layer provided on a UV transmissive base. In this method, the disc substrates are bonded together, so that the information recording layer of one disc substrate faces the other disc substrate, by employing UV irradiation to cure a UV curable composition used as a bonding agent. In the case of the present invention, to cure the bonding agent, UV is irradiated in a single or repeating flash so as not to impair the information recording layer. As a result, the bonding agent can be cured in a shorter period of time with less energy consumed as compared to the conventional method of using continuous irradiation of UV light to cure a UV curable composition used as a bonding agent. Accordingly, the present method enables a product disc to be obtained in a shorter time, with less energy used, so that productivity (i.e., number of bondings per unit time) is improved.

Growing community of inventors

Kawagoe, Japan

Kazuo Murakami