Title:
銀の耐曇性強化
Document Type and Number:
Japanese Patent JP2006523266
Kind Code:
A
Abstract:
An alkanethiol, alkyl thioglycollate, dialkyl sulfide or dialkyl disulfide may be used to surface treat of an alloy of silver containing an amount of germanium that is effective to reduce firestain and/or tarnishing. The treatment has been found to further reduce tarnishing of the alloy such that a sample can be supported close above a 20% solution of ammonium polysulphide for at least 30 minutes while retaining a generally untarnished appearance. The treatment may be carried out at the end of manufacturing a shaped article to give rise to an article that will preserve its untarnished appearance both during transit to a point of sale but during subsequent display for an extended period. The invention therefore also includes a method for manufacturing a tarnish-resistant silver article, which comprises the steps of forming a shaped article of an alloy of silver containing an amount of germanium that is effective to reduce firestain and/or tarnishing, surface treating the article with an alkanethiol, alkyl thioglycollate, dialkyl sulphide or dialkyl disulphide; and introducing the article into packaging. Also disclosed for use in treating an alloy of silver as aforesaid is a water-based composition comprising a treatment agent selected from an alkanethiol, alkyl thioglycollate, dialkyl sulfide or dialkyl disulfide and a mixture of an anionic surfactant and an amphoteric or nonionic surfactant in a concentration that is effective to solubilise the treatment agent.
Inventors:
Johns, Peter, Gaymon
Harrison, Claire, Elizabeth
Harrison, Claire, Elizabeth
Application Number:
JP2006506057A
Publication Date:
October 12, 2006
Filing Date:
March 30, 2004
Export Citation:
Assignee:
MIDDLESEX SILVER CO.LIMITED
International Classes:
C23F11/00; C22C5/06; C22C5/08; C23F11/16
Attorney, Agent or Firm:
Yoshiyuki Osuga