Abstract: An erasing apparatus for a magnetic recording medium is provided to instantaneously remove data recorded on the recording medium, so that the erased data is no longer readable. The erasing apparatus includes a transporter for carrying the recording medium to magnetic field, a positioner for setting the recording medium in position, an electromagnet for generating magnetic field, and a power source for the electromagnet.

Abstract: An ultraviolet-hardenable adhesive for bonding a non-water swellable, ophthalmic-lens to a support member, in producing a non-water swellable ophthalmic lens, the adhesive containing at least one photopolymerizing monomer, and at least one photoinitiator, the at least one photopolymerizing monomer being selected from the group consisting of acrylates or methacrylates represented by following general formulas (I) and (II): ##STR1## wherein R.sub.1 is hydrogen or methyl,R.sub.2 is hydrogen or methyl,R.sub.3 is hydrogen or methyl,m is a positive integer from 2 to 20, andn is a positive integer from 1 to 5.A method of bonding a lens blank to a support member with an adhesive, and a processing of manufacturing a lens using an adhesive, are also disclosed.

Abstract: An ultraviolet-hardenable adhesive for bonding a waterswellable, ophthalmic-lens blank to a support member, the adhesive containing at least one photo-hardenable silicone oil, and at least one photoinitiator, the at least one silicone oil being selected from polysiloxanes represented by the following general formula: ##STR1## wherein each of R.sub.1 to R.sub.3 is methyl or ethyl; n.sub.1, n.sub.2 and n.sub.3 are positive integers which satisfy the specified three formulas;X.sub.1 is --CH.sub.2).sub.3, or ##STR2## A.sub.1 is ##STR3## wherein R.sub.4 is hydrogen or methyl; and B.sub.1 is ##STR4## A method of bonding a lens blank to a support member with an adhesive, and a processing of manufacturing a lens using an adhesive, are also disclosed.

Abstract: An ultraviolet-hardenable adhesive for bonding a water-swellable, ophthalmic-lens blank to a support member, the adhesive containing at least one photo-hardenable silicone oil, and at least one photoinitiator, the at least one silicone oil being selected from polysiloxanes represented by the following general formula: ##STR1## wherein each of R.sub.1 to R.sub.3 is methyl or ethyl; n.sub.1, n.sub.2 and n.sub.3 are positive integers which satisfy the specified three formulas; X.sub.1 is ##STR2## A.sub.1 is ##STR3## wherein R.sub.4 is hydrogen or methyl; and B.sub.1 is ##STR4## A method of bonding a lens blank to a support member with an adhesive, and a processing of manufacturing a lens using an adhesive, are also disclosed.

Abstract: An ultraviolet-hardenable adhesive for bonding a non-water swellable, ophthalmic-lens blank to a support member, in producing a non-water swellable ophthalmic lens, the adhesive containing at least one photopolymerizing monomer, and at least one photoinitiator, the at least one photopolymerizing monomer being selected from the group consisting of acrylates or methacrylates represented by following general formulas (I) and (II): ##STR1## , wherein R.sub.1 is hydrogen or methyl,R.sub.2 is hydrogen or methyl,R.sub.3 is hydrogen or methyl,m is a positive integer from 2 to 10, andn is a positive integer from 1 to 5.A method of bonding a lens blank to a support member with an adhesive, and a processing of manufacturing a lens using an adhesive, are also disclosed.

Abstract: An oxygen permeable soft contact lens material having an improved oxygen permeability, improved softness and transparency prepared by copolymerizing a mixture comprising(a) a polyorganoxiloxane having polymerizable groups containing an unsaturated bond and hydrophilic groups containing a hydroxyl group in the molecular side chains, each of said side chains having a polymerizable group and a hydrogroup, and(b) a monomer having silylated hydroxyl groups as main components, and subjecting the resulting copolymer to desilylation.

Abstract: A copolymer comprising,(a) a hydrophilic siloxanylalkyl ester having a structure in which a siloxane part (1) having a terminal acryloyl or methacryloyl group and a siloxane part (2) having a terminal hydrophilic group are bonded through an alkylene chain with each other,(b) a hydrophilic monomer, and(c) a hydrophobic monomeris suitable for use in the production of a soft contact lens having a high oxygen permeability and an excellent affinity for the eye tissue which can be worn continuously for a long period of time.

Abstract: A method of coloring a water-absorbable plastic partially or totally in a single color or multiple colors in such a manner that no migration or separation of the coloring agents used can take place. A copolymer of a coupler monomer and a water-absorbable plastic monomer, a polymer of a coupler polymer and a water-absorbable plastic monomer or a polymer of a coupler monomer and a water-absorbable plastic polymer is formed into an intermediate product shaped in the form of any desired final product. The intermediate product is immersed in an aqueous solution of a developer consisting of a diazonium double salt and allowed to swell, whereby the diazo-component of the developer penetrates into the plastic. The swollen product is then immersed in an aqueous acid or alkaline solution having an optimum pH value for coupling reaction to allow formation of an azoic dye on the plastic as a result of the coupling reaction.

Abstract: A novel methacrylic acid ester derivative, methyldi(trimethylsiloxy)sylylpropylglycerol methacrylate which is availably employed as a main monomer for preparing copolymers useful as a material of contact lenses. The derivative has siloxane bond which contributes to increase of the oxygen permeability of its copolymers, and has hydrophilic hydroxyl group and ether bond by which the derivative is miscible with a hydrophilic monomer in all proportions and is easily copolymerizable therewith and colorless transparent copolymers are obtained.