3M Innovative Properties Company

Katsuya Takamori

Kazuta Saito

Sumita Basu Mitra

Yorinobu Takamatsu

Sana Fujii

Methods for preparing multi-layer optical laminates include placing an optical film that is free form an adhesive layer between first and second glass substrates that are free of an adhesive layer, placing this laminate under vacuum, and then heating the laminate under pressure to a temperature above the softening temperature of the optical film. The glass substrates are free of an adhesive layer but may include a silane surface treatment. The resulting multi-layer laminate is optically clear and does not show scattering of reflected light by the optical film.

Method for preparing multi-layer optical laminates

The invention provides a two-part adhesive composition making it possible to mutually bond disk substrates within a relatively short time and to produce an optical disk, and an optical disk having a metal film, corrosion of which is restricted under a high-temperature high-humidity condition, and which is produced by using the two-part adhesive composition. A two-part adhesive composition of the invention comprises first and second parts each containing urethane acrylate having a polytetramethylene glycol skeleton and an acrylate having a hydroxyl group in its molecule, wherein the first part further contains a diacyl peroxide and the second part further contains a tertiary amine. Organic peroxide is preferably diacyl peroxide and a setting promoter is preferably a tertiary amine. Either one, or both, of the first and second parts may further contain a photo-polymerization initiator.

Adhesive composition and optical disk using the composition

A bonded optical disk comprising first and second transparent substrates bonded with a light-permeable, pressure sensitive adhesive layer and at least one information recording layer wherein the pressure sensitive adhesive layer has been formed from a pressure sensitive adhesive precursor, having a viscosity of 10 to 5000 cps and being applied onto at least one of the first substrate and the second substrate by radiation curing and has a gel fraction of not less than 50% and a storage modulus of 1.0&times;10,to 1.0&times;10,dyn/cm,at 25&deg; C., or in place of the pressure sensitive adhesive layer, an adhesive layer derived from a radiation curable adhesive precursor having a viscosity of 500 to 10000 cps, and the adhesive precursor is subjected to a higher pressure than an atmospheric pressure, prior to being irradiated, as well as a method and an apparatus for producing a bonded optical disk.

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Tokyo, Japan

Katsuya Takamori