U.S. Philips Corporation

Adriaan J Op Het Veld

Gerardus J Lippits

Rinse Dijkstra

Arnoldus J Van Den Broek

Jelis De Jonge

Adrianus R Engelfriet

Theodorus J Van Vucht

The invention relates to a method of reproducing plastics record carriers, in particular duplicating video records. According to the invention, a metal die is used which is provided with a thin-liquid molding resin of a particular composition which can be polymerized by radiation. A radiation-pervious substrate which is manufactured from synthetic material, for example polymethylmethacrylate, is provided on the molding resin. The molding resin is exposed to light via the substrate after which the cured molding resin together with the substrate connected thereto is removed from the die. The molding resin used in the process comprises low-molecular monomers or oligomers which contain on an average 25-70% by weight of hydrocarbon groups and/or phenyl groups. The molding resin is aprotic and has a functionality as regards unsaturatedness which is between the values 2 and 6. A suitable molding resin contains mono-, tri- or tetra esters of acrylic acid. The molding resin preferably has a swelling capacity with respect to the substrate and for that purpose preferably comprises a vinylmonomer. The metal die used in the method preferably is a quite flat die which is obtained by providing the master disk which is a flat glass plate with information track with a nickel layer, gluing hereon a flat stiffening plate and then removing the master disk. The resulting father disk may be used as a die. Alternatively, further metal copies may be made herefrom which are provided in a simpler manner with a flat stiffening plate. The invention also extends to the molding resin, substrate and die used in the method, as well as the resulting plastics record carriers.

Method of manufacturing a die for duplicating plastics information

The disclosure relates to the manufacture of wire-drawing dies. The disclosure provides a method for securing a core in a metal housing. The method begins with the clamping of an annulus, consisting of a hardenable metal alloy, around a cylindrical core consisting of a material such as polycrystalline diamond or boron nitride. The core is clamped so as to produce a permanent, radially compressive stress therein. The core-annulus combination is secured in a metal housing of a conventional shape.

Method of producing a drawing die

The invention relates to a method of reproducing plastics record carriers, in particular duplicating video records. According to the invention, a metal die is used which is provided with a thin-liquid molding resin of a particular composition which can be polymerized by radiation. A radiation-pervious substrate which is manufactured from synthetic material, for example polymethylmethacrylate, is provided on the molding resin. The molding resin is exposed to light via the substrate after which the cured molding resin together with the substrate connected thereto is removed from the die. The molding resin used in the process comprises low-molecular monomers or oligomers which contain on an average 25-70% by weight of hydrocarbon groups and/or phenyl groups. The molding resin is aprotic and has a functionality as regards unsaturatedness which is between the values 2 and 6. A suitable molding resin contains mono-, tri- or tetra esters of acylic acid. The molding resin preferably has a swelling capacity with respect to the substrate and for that purpose preferably comprises a vinylmonomer. The metal die used in the method preferably is a quite flat die which is obtained by providing the master disk which is a flat glass plate with information track with a nickel layer, gluing hereon a flat stiffening plate and then removing the master disk. The resulting father disk may be used as a die. Alternatively, further metal copies may be made herefrom which are provided in a simpler manner with a flat stiffening plate. The invention also extends to the molding resin, substrate and die used in the method, as well as to the resulting plastics record carriers.

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Eindhoven, Netherlands

Adriaan J Op Het Veld