Schott Glas

Roland Buerkle

Marten Walther

Andreas Habeck

Dirk Schlatterbeck

Reiner Mauch

Andreas Weber

Andreas Berndt

Torsten Otto

Oliver Scherer

Inka Henze

A method of protecting a glass substrate, especially a display glass or a hard disk blank made from a glass or a glass-ceramic, from unacceptable surface damage and scratches, often leading to glass breakage, during processing and transport, is described. This protective method includes applying a removable protective coating made of at least one polymer layer, or at least one polyvinyl alcohol layer, to the glass substrates by spraying or rolling the polyvinyl alcohol or a polymer solution of the polymer to be applied in a polar organic solvent, onto the glass substrate, or dipping the substrate into it. Then when the substrate is ready for its end use, the protective coating is removed by washing in water or polar organic solution so that a residue does not remain on it. The glass substrates, protected in this manner have outstanding surface quality and improved hard disk blanks can be economically produced from them.

Method of protecting glass substrate surfaces

A method and an apparatus for cutting a laminate made of a brittle material and a plastic with a cutting tool is described. The plastic is heated up, thereby lowering its viscosity, at least in the region of a predetermined cutting line. A cutting tool is placed onto the plastic side of the laminate, the loading pressure being adjustable. By moving cutting tool relative to the laminate along the predetermined cutting line, the plastic is severed; at the same time the brittle material is scored, thereby inducing a mechanical stress. If appropriate, the mechanical stress along the cutting line is subsequently increased to exceed the rupture strength of the scored brittle material. A preferred application is the cutting of thin glass or glass-ceramic/plastic laminates.

Method and apparatus for cutting a laminate made of a brittle material and a plastic

The apparatus for cutting a laminate, which is made of a brittle material and a plastic, has a cutting tool for severing the plastic along a predetermined cutting line and simultaneously scoring the brittle material; a heating device for heating the plastic along the cutting line; a device for pressing the cutting tool with an adjustable pressure on the laminate; a device for moving the engaged cutting tool along the cutting line to simultaneously sever the plastic and score the brittle material and a controller for controlling the heating device so that during the severing and scoring a temperature of the cutting tool is maintained constant and the heating is sufficient to lower viscosity of the plastic along the cutting line so that a predetermined loading pressure of the cutting tool on the laminate necessary for simultaneously scoring the brittle material and severing the plastic is not exceeded, whereby uncontrollable fracture of the brittle material does not occur.

A method of protecting a surface of a display glass or a hard disk substrate during processing arid transport includes applying at least one polyvinyl alcohol or other polymer protective layer on the surface, which is soluble in polarorganic solvents, so that the layer can be removed after processing and transport by washing in heated water or a polar organic solvent without leaving residues on the surface. The polyvinyl alcohol used to make the protective coating has an average molecular weight of &gE; about 60,000 g/mol and a hydrolysis degree of &gE;95% and the at least one polyvinyl alcohol layer is dried by heating at temperatures of about 150&deg; C. or less to form the protective coating after applying the polyvinyl alcohol layer. The other polymers are less soluble in water than polyvinyl alcohol but are easily removed with organic solvent.

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Nieder-Olm, Germany

Roland Buerkle