Abstract: A method is described of preparing a tin-silver (Sn—Ag) alloy plating solution containing methanesulfonic acid tin, methanesulfonic acid silver, methanesulfonic acid, and an additive, wherein the method includes: (a) eliminating impurities such as released chloride compounds and released sulfur compounds, which are present in the methanesulfonic acid, (b) preparing the methanesulfonic acid tin and the methanesulfonic acid silver by dissolving, through an electrolytic process, tin and silver in the methanesulfonic acid from which the impurities are eliminated; (c) producing a mixture solution by adding the methanesulfonic acid, the methanesulfonic acid tin, the methanesulfonic acid silver, and the additive; and (d) filtering the mixture solution. And by the method thereof, current efficiency may be increased and a desirable plating film may be maintained by eliminating the impurities from the methanesulfonic acid used as a base material and preparing the Sn—Ag alloy plating solution.

Abstract: A fire door includes an inner plate forming an inner side of the fire door; an outer plate opposing the inner plate to form an outer side of the fire door; adhesive layers applied to opposing surfaces of the inner and outer plates; a pair of reinforcing brackets vertically attached to opposite edge portions between both of the inner and outer plates; and a sound absorbing material filled in a space defined by the inner and outer plates and the reinforcing brackets. The inner and outer plates are made of a bonded steel plate, which includes a surface sheet exposed to the inner or outer side of the fire door, a backing sheet supporting the surface sheet, and an adhesive material interposed between the surface sheet and the backing sheet and bonding the surface sheet and the backing sheet together. The fire door has excellent sound absorbing and fireproof properties.

Abstract: A bonded plate for a sink bowl, which has excellent sound-absorbing, vibration-damping, and heat-insulating characteristics, and a method of forming the sink bowl using the same through pressing. The bonded plate includes a surface plate, a backing plate backing the surface plate, and an adhesive resin interposed between the surface plate and the backing plate and bonding the surface plate and the backing plate with each other, wherein the adhesive resin has a thickness from about 0.02 mm to about 0.1 mm. Thereby, the adhesive resin layer of the bonded plate can have sound-absorbing, vibration-damping, and dew-condensation-preventing functions. Further, the sink bowl is produced using the bonded plate, so that it can reduce the cost of production, can provide formability equal to that of the conventional sink bowl, and can produce excellent sound-absorbing, vibration-damping, and dew-condensation-preventing effects.

Abstract: An elevator panel having excellent sound-absorbing and vibration-damping characteristics, and an elevator car using the same. The elevator panel includes a surface plate; a backing plate backing the surface plate; and an adhesive resin interposed between the surface plate and the backing plate to bond the surface plate and the backing plate with each other, wherein the adhesive resin has a thickness from about 0.02 mm to about 0.1 mm. Thereby, the elevator panel can reduce the cost of production, provide an external appearance equal to that of the conventional elevator panel formed of expensive metal material, and produce excellent effects of isolating and absorbing sounds such as noise from the outside.