Abstract: The optical recording medium of this invention includes: a first substrate having a first information surface; a semitransparent reflection film formed on the first information surface of the first substrate; a second substrate having a second information surface; a reflection film formed on the second information surface of the second substrate; and an adhesive layer for adhering the first substrate and the second substrate so that the first information surface and the second information surface face each other, wherein the thickness of the first substrate is 0.56 mm or more, the thickness of the adhesive layer is 30 &mgr;m or more, and the total thickness of the first substrate and the adhesive layer is 0.68 mm or less.

Abstract: Methods for forming a single-side-readable DVD having graphical information viewable from the DVD's frontside disc are provided. A first, frontside disc having a first and a second surface, with the second surface comprising program information and coated with a semi-reflective coating, is bonded to a second, backside disc having a third and a fourth surface. A first portion of the fourth surface comprises spillover program information and a second portion of the fourth surface comprises graphical information. The fourth surface is coated with a reflective coating. During DVD formation, the frontside and backside discs are adhesively bonded back to back so that the second surface of the frontside disc faces the fourth surface of the backside disc. Because the frontside disc comprises a semi-reflective coating, the graphical information on the second portion of the fourth surface of the backside disc is viewable through the frontside disc.

Abstract: An optical disk of the present invention includes a first substrate having a signal area on a principal plane and a central hole, and a second substrate that is transparent and attached to the first substrate. The second substrate is thinner than the first substrate, and has a central hole whose diameter is larger than that of the first substrate. The first substrate and the second substrate are attached to each other with radiation curable resin (adhesive member) disposed therebetween so as to extend at least from an inner peripheral edge of the second substrate to an outer peripheral edge thereof.

Abstract: The present invention relates to a multi-layered disc-shaped information recording medium having a plurality of signal recording layers each carrying information signals. In preparing the recording medium, a first substrate obtained on punching a sheet obtained in turn by having a signal recording pattern transcribed on it from a first stamper and by forming a semi-transparent film on a signal surface is bonded to a second substrate obtained on injection molding a synthetic resin material. The second substrate is prepared by having transcribed to it a signal recording pattern formed on a second stamper provided on an injection molding device. A reflective film is formed on a signal surface having the transcribed second substrate. The first and second substrates are bonded together on their signal recording layers by a transparent adherent layer.

Abstract: The present invention provides a heat-sensitive recording material including a support having disposed thereon at least two heat-sensitive recording layers and an intermediate layer provided between the heat-sensitive recording layers, wherein the intermediate layer contains a compound having a fusing point or a softening point ranging from 40° C. to 200° C. and a particle size of 0.5 &mgr;m or smaller.

Abstract: An optical disk contains a recording layer and an adhesive layer between at least two substrates, wherein the adhesive layer contains a cationic polymerizable resin (A), a photo-initiator (B), and an anion catcher (C). The weight ratio of the photo-initiator (B) and the anion catcher (C) is preferably from 3:1 to 3:24, more preferably from 3:1 to 3:12.

Abstract: 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° 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/m2·day or less, the object described above is achieved.

Abstract: A laminated disc composed of at least two supporting discs superposed upon another, each of the supporting discs having a thickness of 0.01 to 1 mm and being made of a vinyl alicyclic hydrocarbon polymer. This laminated disc is used as an optical disc including digital video disc (DVD).

Abstract: 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.

Abstract: An article is disclosed that includes a) a first polycarbonate substrate; b) a second polycarbonate substrate; and c) an adhesive composition disposed between the first polycarbonate substrate and the second polycarbonate substrate such that the first polycarbonate substrate is bonded to said second polycarbonate substrate through the adhesive composition; the adhesive composition includes an adhesive polymer that includes the reaction product of 1) an N-vinyl containing monomer selected from the group consisting of N-vinyl caprolactam, N-vinyl pyrrolidone, and N-vinyl imidazole, and combinations thereof, and 2) an acrylic acid ester monomer of a non-tertiary alcohol having an alkyl group that includes 4 to 20 carbon atoms.

Abstract: An optical disc used with an optical head with a focus depth of about 2 micron meter minimizes defects and deterioration in the optical disc at the time of manufacture, during operation and storage thereof as well. The optical disc includes a pair of transparent substrates each provided with at least one layer enabling recording of information, with the pair being bonded and laminated together has an instantaneous axial acceleration<2G.

Abstract: A photocurable resin composition comprising:

Abstract: An optical information medium includes a support substrate (20) having an information recording layer (4) on one surface, and a light transmissive layer (2) thereon, wherein writing and/or reading light enters the information recording layer (4) through the light transmissive layer (2). The light transmissive layer (2) includes a light transmissive resin sheet (201) and an adhesive layer (202) of a UV-curable resin joining the light transmissive sheet to the support substrate and having an average thickness from 0.5 &mgr;m to less than 5 &mgr;m. The light transmissive layer has a uniform thickness, minimized optical heterogeneity, and least increased birefringence and is effective for restraining medium bowing.

Abstract: A hot-melt web has a buffer adhesive layer of a thermosetting resin on a light transmissive, heat resistant resin support. The hot-melt web has the advantages of light transparency, heat resistance, weather resistance, controlled entrainment of bubbles and easy removal of bubbles during thermocompression bonding, provides a sufficient bonding force, and effectively corrects random deformations of a module sheet. The hot-melt web is suitable for use in the bonding, joining and laminating steps in the manufacture of optical discs such as DVD and flat panel displays, is easy to eliminate bubbles, and is effective for improving the quality of an associated product. A laminate using the hot-melt web and a method for preparing the laminate are also provided.

Abstract: 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.

Abstract: A compact digital disk assembly having a label which extends over substantially all of the upper surface of the disk, thereby facilitating the display of artistic and textual information uninterrupted by a center cutout normally found on compact disks. The assembly includes a conventional compact disk having a center cutout, a CD plug insertable in the cutout, and a label having a removable portion extending over the cutout. The label is affixed to the upper surfaces of the CD and the CD plug with a pressure sensitive adhesive.

Abstract: An optical disc used with an optical head with a focus depth of about 2 micron meter minimizes defects and deterioration in the optical disc at the time of manufacture, during operation and storage thereof as well. The optical disc includes a pair of transparent substrates each provided with at least one layer enabling recording of information, with the pair being bonded and laminated together has an instantaneous axial acceleration<2 G.

Abstract: The object of the present invention is to provide an optical disc and a method of manufacturing thereof wherein defects and deterioration in the optical disc are minimized at the time of manufacture, during operation and storage thereof as well. The invention conceives an optical disc suitable for accomplishing the above object through specifications such as providing a cross-sectional structure thereof comprising a pair of transparent substrates each provided with at least one layer of a recording film formed on the surface of information patterns thereof, with the pair being bonded and laminated with an adhesive, and further providing an instantaneous axial acceleration<2 G measured at room temperatures, a skew angle<5 mrad measured at room temperatures, and a skew angle<5 mrad measured after being left for one hour as heated to 80° C. (otherwise, a shear mass<20 &mgr;m measured after being left for one hour as heated to 80° C.

Abstract: Cationic and hybrid radiation-curable pressure sensitive adhesive compositions for digital versatile discs and other substrates, a method for bonding versatile digital disc layers together with a cationic or hybrid radiation-curable pressure sensitive adhesive, and a digital versatile disc bonded by cationic or hybrid radiation-curable pressure sensitive adhesive.

Abstract: An epoxy resin composition according to the present invention is one initiating cationic polymerization upon irradiation with energy rays. The epoxy resin composition is formed of at least bisphenol type epoxy resin (A) as an active ingredient, epoxy resin (B) shown in the following formula and cationic polymerization catalyst (C). The epoxy resin composition can improve the thermal resistance of the adhesive layer in an optical information recording medium, and the adhesive property of the adhesive layer is not lowered even if its hardness is increased or it is in high humidity.

Abstract: 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.

Abstract: A photocurable resin composition which comprises (A) a urethane (meth)acrylate oligomer obtained by the reaction of (a) at least one polyol compound preferably selected from the group consisting of polyester polyols and polycarbonate polyols, (b) a polyisocyanate compound, and (c) a hydroxyl group-containing (meth)acrylate compound; (B) a (meth)acrylolylphosphate; (C) a multifunctional (meth)acrylate compound; and (D) a photopolymerization initiator and, optionally, (E) an organosilyl-containing mercapto compound. The composition exhibits a fast cure speed, and the cured products obtained from the composition exhibit superior adhesion under high temperature-high humidity conditions and metal corrosion properties.

Abstract: An article is disclosed that includes:

Abstract: The present invention relates to a composition comprising a first monomer having the formula CH2═CHCOOR1, where R1 is a linear alkyl group having from 9 to 16 carbon atoms or a branched alkyl group having from 9 to 30 carbon atoms, and whose homopolymer has a Tg less than 0° C.; and/or a second monomer having the formula CH2═CHCOOR2, where R2 is an alkyl group having at least 9 carbon atoms whose homopolymer has a Tg greater than 15° C.; and a third component which may be another monomer, a polymer, surface-modified particles, or combinations thereof as well as article comprising the composition.

Abstract: Ultraviolet rays are irradiated in a space through which a cationic ultraviolet curable composition falling from a nozzle passes before reaching a disc substrate. The cationic ultraviolet curable composition which has been irradiated with ultraviolet rays, is distributed in a ring form on the surface of the disc substrate. Another disc substrate is then superposed in this distributed surface to spread the composition by pressing or by the weight of the other disc substrate itself.

Abstract: Information-bearing discs are fabricated from a first disc and a second disc. The first disc has a first substantially planar surface and a second surface opposite to the first surface. The second surface has first information recorded on it by means of local changes in the distance of the second surface from the first surface. The thickness of the second disc is not equal to the thickness of the first disc and has opposite, substantially planar, third and fourth surfaces. The fourth surface may have second information recorded on it by means of local changes in the distance of the fourth surface from the third surface. The second disc is secured to the first disc so that the fourth surface faces the second surface.

Abstract: A device cures an adhesive by means of UV radiation in an inert-gas atmosphere. The adhesive is interposed as an adhesive layer between two superposed layers of a disc-shaped information carrier. The device includes a UV source, a supplier for an inert gas, and a holder for holding the information carrier in a centered position with respect to a centering axis. The inert-gas supplier has discharge openings for inert gas, situated in a circular zone around the centering axis, at a distance from the centering axis which substantially corresponds to the radius of the peripheral edge of the information carrier, so as to cause inert gas to flow past the peripheral edge during curing, as a result of which locally present oxygen which would interfere with curing is expelled.

Abstract: The invention relates to an adhesive for optical disks exhibiting superior adhesive properties with resins such as polycarbonate or metals such as aluminum and gold, and possessing better wet heat resistance than conventional adhesives. The adhesive comprises (A) a urethane (meth)acrylate oligomer (B) a hydroxy (meth)acrylate in which the hydroxy group is 3 or more carbons spaced away from the (meth) acrylate, and (C) at least one photoinitiator.

Abstract: An improved substrate and stamper holder and method of forming substrates are disclosed. According to a preferred embodiment of the invention, a substrate for a DVD has a moat with a capillary barrier shape. Under one embodiment, the moat has a region with an abrupt outer diameter transition. One embodiment has the outer diameter transition at approximately at a right angle relative to a registering surface of the substrate. Another embodiment of the invention provides a wider moats. The improvements reduce the likelihood of resin wicking past the moats.

Abstract: A process for the preparation of high-quality magnetic dispersions having an Hc>120 kA/m, a residual induction Mr/Mm≧0.9 and an orientation ratio of about 2.

Abstract: An ultraviolet-curable adhesive composition comprising a photopolymerization initiator whose molar absorption coefficient at a wavelength of 360-450 nm is at least 400 and an ultraviolet-curable compound. The adhesive composition of this invention can bond substrates which show transmittances of 0.01-20% to all of energy beams of a wavelength of 280-380 nm, to one another.

Abstract: The present invention provides a label for optical disks which comprises a base sheet having a coefficient of linear expansion of 1.0×10−5 to 12.0×10−5 and a thermal shrinkage ratio of 3 or below percent, a display formed on at least one surface of the base sheet, and an adhesive layer formed on a surface of the base sheet or the display. The label for optical disks can be applied on the surface of the optical disk with displays such as various printings and pholograms, and can provides an optical disk having beauty and fineness in aesthetic.

Abstract: An ultraviolet-curable adhesive composition comprising a photopolymerization initiator whose molar absorption coefficient at a wavelength of 360-450 nm is at least 400 and an ultraviolet-curable compound. The adhesive composition of this invention can bond substrates which show transmittances of 0.01-20% to all of energy beams of a wavelength of 280-380 nm, to one another such as base boards for an optical disk.

Abstract: The present invention provides an optical disc provided with a watermark inside, which is visible with naked eyes from a reproduction side of the optical disc, and the producing method and the production apparatus thereof. The optical disc comprises a transparent substrate having an information signal recorded surface, a reflective layer formed on the information signal recorded surface thereof, an adhesive layer formed on the reflective layer, a mask layer on the adhesive layer and a transparent dummy substrate on the mask layer stacked in this order. The adhesive layer is made of an adhesive of which curing speed is changed according to a controlled amount of radiation of ultraviolet rays. The watermark is recorded in the optical disc by irradiating the ultraviolet rays on the adhesive through the mask layer provided with light shielding members to cause the adhesive to be cured by controlling a curing speed of the adhesive corresponding to existence or nonexistence of the light shielding members.

Abstract: An optical disc used for information recording capable of suppressing an increase of birefringence of the light-transmitting layer at the minimum, resulting in an optical disc having a high quality without a degradation of signal characteristics. The optical disc has a substrate having a group of pits/grooves representing information signal on a surface thereof, a reflecting layer formed on the substrate, and a resin film formed on the reflecting layer through an adhesive layer, wherein a thickness of the adhesive layer is made to be not more than 100 &mgr;m, and a product value of a photoelasticity constant, a modulus of tension elasticity and a thickness with respect to the resin film is established within −0.2 to 0.2 mm.

Abstract: A multilayer optical disk having an information storage layer which can as well as be reproduced by a general purpose reproducing apparatus, for example, a compact disk player, and from which information can be read from other information storage layers by using an exclusive reproducing apparatus. The method of manufacturing a multilayer disk comprises the steps of forming a first substrate having a first information storage area enabling reproduction of information therein with a first light beam having a wavelength of 770 nm to 830 nm; forming a second substrate having a second information storage area enabling reproduction of information therein with a second light beam having a wavelength of 615-655 nm but which is relatively transparent with respect to said first light beam; and bonding said first substrate to said second substrate together without said first and second said information areas facing each other.

Abstract: Hotmelt adhesives with a melt viscosity of >100,000 mPas at 160° C. are suitable for bonding substrate halves in the production of digital versatile discs (DVDs) and afford major process-related advantages over known UV-curing adhesives. In their pigmented embodiment, they are able to combine the three functions of adhesive bonding, protecting the metallic reflection layer against corrosion and forming a covering background for a text/graphics layer.

Abstract: 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 1.0×104 to 1.0×107 dyn/cm2 at 25° 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.

Abstract: A method for controlling the bonding layer thickness between facing surfaces of two optical discs having information areas during manufacture of an optical storage apparatus wherein a plurality of microspheres of a predetermined uniform diameter are selectively placed on a facing surface of one of the optical discs. A bonding material is placed on the facing surface of the other of the optical discs. Pressure is thereafter applied to the two optical discs to form a substantially uniform bonding layer thickness between the two optical discs upon curing of the bonding material.

Abstract: Cationic and hybrid radiation-curable pressure sensitive adhesive compositions for digital versatile discs and other substrates, a method for bonding versatile digital disc layers together with a cationic or hybrid radiation-curable pressure sensitive adhesive, and a digital versatile disc bonded by cationic or hybrid radiation-curable pressure sensitive adhesive.

Abstract: A method for making a DVD-18 disc using primarily just conventional CD-type injection molding and sputtering equipments. Three substrates are molded. Each of two of the substrates has just one metallic information layer, with the opposite side being flat. The third substrate has two metallic information layers on its opposite sides. The three substrates are arranged in a sandwich configuration, with the substrate having two information layers being in the middle. Each of the outer substrates has a semireflective (gold) information layer that faces inwardly of the sandwich. The middle substrate has two fully reflective (aluminum) information layers. A very thin layer of glue is placed between the semireflective information layer on each of the outer substrates and one of the fully reflective information layers on the middle substrate.

Abstract: An adhesive composition including (a) a polymerizable (meth)acrylate compound having a phosphate group, (b) a thiol compound, (c) a polymerizable compound having a double bond and having no phosphate group, and (d) a photopolymerization initiator. The adhesive composition is suitably used for fabrication of optical discs.