KR20080093941A - Noncatalytic silver foam - Google Patents

Abstract

A silver foam is provided to prevent contamination of a silver plating solution by carrying out electroless silver plating right after etching and silver nitrate deposition steps, and to avoid a need for spraying a large amount of expensive silver. A silver foam is obtained by a continuous method comprising the steps of: etching a polyurethane foam with 5% aqueous sodium hydroxide solution, followed by neutralization with acetic acid; and dipping the foam into silver nitrate/sodium hydroxide/aqueous ammonia to perform sensitization, activation and acceleration. The silver foam obtained from the method is used particularly in a system requiring instant sterilization activity including a water purifying system, water softening system, or alkaline ionic water treating system.

Description

 Instant disinfectant silver foam manufactured by non-catalytic process {Noncatalytic Silver foam}

There are three processes for casting silver foam and sintering. Among them, when etching is performed on the PU foam during the manufacturing process of silver foam by the plating method, craters are formed on the surface of the PU foam, and palladium chloride (PdCl ₂ ) particles are fixed in the crater. This is called the anchor effect, which improves the adhesion between silver and resin in electroless silver plating. Palladium chloride particles are a pretreatment process for initiating a chemical reaction on the resin surface, which is a non-conductor during electroless silver plating.

As described above, the present invention omits the catalytic process and combines the activation process and the acceleration process into one process, and is electroless plating.

Silver is generally known to have antibacterial and bactericidal activity.

Strongly combined with silver bacterium of -SH, -COOH, OH to disturb the function of breaking the cell membrane or the cell membrane of the bacteria and the antibacterial action, the oxygen to the silver catalyzed O ^{2 -} is converted ^to, O ^{2 +,} O It is known to have a bactericidal action.

Silver has long been harmful to humans so that it can be used in foods, and has a bactericidal effect even at very low concentrations of 1 ppm or less.

(Reference 1) Nano (Nano Silver), 「KISTI Technical Information Analysis Report」, Korea Institute of Science and Technology Information, 2004,12

(Document 2) Hye Won Jung, Hyun Sook Kim, Treatment of Silver Colloidal Solution in Washing Process for Antimicrobiality, Journal of the Korean Society of Clothing and Textiles, 28 (9/10), pp.1312-1319,2004

Maximized surface area for maximum sterilization of silver (specific surface area 2700 mm ² / mm ³ If it is made in the state of 3D network structure, it has perfect sterilizing power even at 1.5ℓ / min, which is the water discharge pressure of general water purifier.

There are three ways to make the ideal open pore metal foam. First is casting

(Document 3) 10-2000-0012491

As the second sintering method

(Document 4) 10-2003-0056790

Third is plating method

(Document 5) 10-0546512-0000, 10-0565006-0000, 10-0472967-0000

Patents are registered as a method of imparting conductivity to polyurethane filter foams in different plating methods.

There are three patents of silver foam manufactured by the above-described plating method. All of them are conductive and PU-plated by electroless silver plating. The difference between the three patents is that they are conductive to PU foam. How to grant.

The first method is to attach graphite particles to the surface of PU foam, and the third patent is to spray silver powder on the PU surface by spraying with adhesive. This method may cause contamination of the electroless plating solution or the electroplating solution and cause big loss. There is. In addition, since electroplating requires that the sprayed coating film have a thickness greater than the critical thickness, a considerable amount of silver powder is consumed, resulting in an increase in cost.

The second method is a method of plasma sputtering a PU foam in vacuum, which has a disadvantage in that silver powder particles are not applied to a thick material. In addition, vacuum sputters are quite expensive, which increases the price of the product.

In general, electroless silver plating is performed through degreasing-etching-neutralization-sensitization-activation-acceleration-process.

The present invention is to improve the process to significantly reduce the production cost by degreasing the PU foam with detergent to remove dust or grease, and then washed with water (this process can be omitted because impurities are removed in the next process) and reduced alkali The solution was neutralized with acetic acid after an etching process in which a 5% aqueous sodium hydroxide (NaOH) solution was maintained at 95 ° C for 30 minutes at a liquid ratio of 50: 1. Silver nitrate (AgNO ₃ ) 1.5g / ℓ + sodium hydroxide (NaOH) 42g / ℓ + 5ml / l ammonia water for 30 minutes by immersion and acceleration process can be solved by one step.

Compared to the conventional method, the etching and nitric acid can be electroless silver plated immediately after two deposition processes, so that the plating solution is not contaminated, and the expensive silver powder can be removed by spraying a large amount of expensive silver powder.

The PU foam was neutralized with acetic acid after an etching process in which a 5% aqueous sodium hydroxide (NaOH) solution was maintained at 95 ° C. for 30 minutes with a liquid ratio of 50: 1. 1.5 g / l of silver nitrate (AgNO ₃ ) + 42 g / l of sodium hydroxide (NaOH) + 5 ml / l of ammonia water was immersed for 30 minutes and electroless silver plated, which was then electroplated to thicken the thickness (100-300 μm). Since electroplating has a critical thickness, it must have a certain thickness of a plating film, and in order to stabilize a plating layer, it is necessary to give a strike treatment preferably.

When the plating process is finished, keep the PU foam at a temperature between 500 ~ 1000 ℃ for 10 ~ 60 minutes to sinter and have ductility.

Claims (2)

PU foam is processed in three processes from etch process to sensitization, activation and acceleration process. The silver foam manufactured by the above-mentioned method is used to be installed in a place where instant sterilization power is required, such as a water purifier, a softener, an alkaline ionizer, and the like.