Background technology
Silver is a kind of malleable, mouldable precious metal, and is the same with gold, because its content in the earth's crust is few, has bright looking simultaneously, thereby be widely used in decoration industry.Decorative electroplating silver requires coating and high base strength height, wear-resisting, anticorrosive and anti-tarnishing ability is strong, and the outward appearance light is careful.Used the most extensive, the maximum bright silver system of research is alkaline cyanide bright plating silver system in the past, but along with the enhancing of people's environmental consciousness, has cyanide silver electroplating to be eliminated gradually.Therefore, Yan Zhi brightening agent for cyaniding plant of silver had been not suitable for the development in future direction in the past, and the exploitation cyanogen-free silver-plating brightener should be a main developing direction from now on.Since non-cyanide bright electrosilvering technology began one's study from the seventies in 20th century, though obtained some achievements, but its technology is still not really ripe, in order to obtain bright silvering, usually need carry out mechanical polishing or chemical bright dipping to the dark silvering that plating obtains, so not only waste great amount of manpower and material resources, also a large amount of silver of waste in polishing process.Also there is employing in the non-cyanide plating silvering solution, to add the report that brightening agent directly obtains the minute surface bright silver plating layer, but to so far, bright silver generally is to adopt organic additive (great majority are to contain to be easy to the sulfocompound that participates in reacting) to obtain bright silver plating layer, the coating of Huo Deing is because sulfur-bearing like this, coating is easy to change, fragility is bigger, and weldability is relatively poor.The report that adds antimonic salt or selenium salt in plating bath is also arranged, but can not obtain satisfied bright coating.
Summary of the invention
The objective of the invention is to that the silvered film that obtains behind the brightening agent is brightless, easy to change at adding in the non-cyanide plating silvering solution, fragility is big, with the unstable problem of basal body binding force, a kind of non-cyanide silver electroplating brightening agent and preparation method thereof is provided.This brightening agent is used for the non-cyanide silver coating system, is the non-cyanide silver coating system of main component with glycolylurea-Silver Nitrate particularly, can obtain the silvered film of minute surface light, and gained coating and basal body binding force are firm, not easy to change.
Cyanogen-free silver-plating brightener of the present invention is made by 0.1～1mol/L piperonylaldehyde, 0.1～2mol/L sodium bisulfite, 0.1～2mol/L trolamine, 0.1～1mol/L butynediol.The preparation method of above-mentioned cyanogen-free silver-plating brightener carries out according to following steps: a, 0.1～2mol sodium bisulfite is made into saturated solution; B, 0.1～1mol piperonylaldehyde is added in the saturated sodium sulfite solution of a step preparation, ultrasonic concussion 30～60min makes whole piperonylaldehydes become the adduct of sodium bisulfite; C, 0.1～2mol trolamine, 0.1～1mol butynediol are dissolved in the solution of b step preparation in addition, add solvent cut, after mixing, promptly get required brightening agent to 1L.
Gained brightening agent of the present invention can be used in the bright non-cyanide silver coating technology.With the brightening agent of the present invention preparation, adding glycolylurea-Silver Nitrate is in the non-cyanide plating silvering solution, can obtain surfacing, crystallization careful, with the strong minute surface bright coating of basal body binding force.In addition because brightening agent of the present invention does not contain the sulfocompound that participates in reaction, overcome the shortcoming that the sulfur-bearing brightening agent is easy to make coating color.Compare with general cyanogen-free silver-plating brightener, on operating procedure, have advantages such as do not contain the sulfocompound that participates in reaction, be easy to preparation, dispersive ability is good.
Embodiment
Embodiment one: the cyanogen-free silver-plating brightener of present embodiment is made by 0.1～1mol/L piperonylaldehyde, 0.1～2mol/L sodium bisulfite, 0.1～2mol/L trolamine, 0.1～1mol/L butynediol.Wherein solvent is any solvent that above-mentioned four kinds of compositions are dissolved each other, the mixed solution of for example water, or second alcohol and water.
Butynediol described in the present embodiment can be 1, the mixture of one or more in 4-butynediol, propoxy-butynediol, the oxyethyl group butynediol.
The cyanogen-free silver-plating brightener of present embodiment is applicable to the non-cyanide silver coating liquid system, and being particularly useful for glycolylurea-Silver Nitrate is the non-cyanide plating silvering solution.The improvement that those skilled in the art carries out according to above-mentioned principle all should belong to protection category of the present invention.
Embodiment two: the cyanogen-free silver-plating brightener of present embodiment is by 0.1mol/L piperonylaldehyde, 0.5mol/L sodium bisulfite, 1mol/L trolamine, 0.5mol/L1, and 4-butynediol, 0.5mol/L propoxy-butynediol are made.
Embodiment three: the brightening agent of present embodiment is by 0.1mol/L piperonylaldehyde, 0.2mol/L sodium bisulfite, 2mol/L trolamine, 1mol/L1, and the 4-butynediol is made.
Embodiment four: the brightening agent of present embodiment is made by 1mol/L piperonylaldehyde, 1.5mol/L sodium bisulfite, 0.5mol/L trolamine, 0.2mol/L propoxy-butynediol.
Embodiment five: the brightening agent of present embodiment is made by 0.3mol/L piperonylaldehyde, 1mol/L sodium bisulfite, 1.5mol/L trolamine, 0.1mol/L oxyethyl group butynediol.
Embodiment six: the brightening agent of present embodiment is by 0.7mol/L piperonylaldehyde, 2mol/L sodium bisulfite, 1mol/L trolamine, 0.5mol/L1, and the 4-butynediol is made.
Embodiment seven: present embodiment is prepared as follows cyanogen-free silver-plating brightener: a, 0.1～2mol sodium bisulfite is made into saturated solution; B, 0.1～1mol piperonylaldehyde is added in the saturated sodium sulfite solution of a step preparation, ultrasonic concussion 30～60min makes whole piperonylaldehydes become the adduct of sodium bisulfite; C, 0.1～2mol trolamine, 0.1～1mol butynediol are dissolved in the solution of b step preparation in addition, add solvent cut, after mixing, promptly get required brightening agent to 1L.
Solvent described in the present embodiment is a water, perhaps is water and alcoholic acid mixture; Described butynediol can be 1, the mixture of one or more in 4-butynediol, propoxy-butynediol, the oxyethyl group butynediol.
Embodiment eight: present embodiment prepares cyanogen-free silver-plating brightener according to following steps: the 0.2mol sodium bisulfite is made into saturated solution; Piperonylaldehyde with 0.1mol is added in the saturated sodium sulfite solution of aforementioned preparation then, and ultrasonic concussion 30min makes whole piperonylaldehydes become the adduct of sodium bisulfite; In addition 2mol trolamine, 1mol butynediol are dissolved in the solution of aforementioned preparation, to 1L, after mixing, promptly get required brightening agent with water or alcohol dilution.
The brightening agent that present embodiment is provided adds in the non-cyanide silver coating plating bath to be electroplated according to a conventional method, can obtain surfacing, the careful minute surface bright coating of crystallization, and this brightening agent is compared with general cyanogen-free silver-plating brightener have following characteristics on operating procedure:
1. the brightening agent that provides of present embodiment does not contain the sulfocompound that participates in reaction in electrodeposition process, and the coating of acquisition is sulfur-bearing not, and the anti-tarnishing ability of coating is strong.
2. the brightening agent that present embodiment is provided adds in the non-cyanide silver coating plating bath to be electroplated according to a conventional method, the coating that obtains is through file test method and bend test method test coating and high base strength, phenomenons such as peeling do not appear in test back coating, come off illustrate that coating and matrix bond are good.
3. after the brightening agent that present embodiment is provided adds the non-cyanide silver coating plating bath, the current efficiency height of plating bath, dispersive ability is good, and current efficiency is 99.1% in the best electroplating technical conditions that the present invention recommends to use, and dispersive ability is 86.2%.
The best electroplating technical conditions that the present invention recommends to use is:
Silver Nitrate 35g/L;
Glycolylurea 170g/L;
Salt of wormwood 50g/L;
Boric acid 10g/L;
Tripotassium Citrate 100g/L;
Brightening agent 10～15mL/L;
20～100 ℃ of temperature;
Cathode current density 0.1～2A/dm2
Anode 99.99% fine silver plate.