Method for removing color spots on surface of silverware

Abstract

The invention provides a method for removing color spots on the surface of a silverware, and belongs to the field of silver product treatment.The method comprises the following steps that the silverware to be treated is placed in a mixed solution of organic acid and hydrogen peroxide to be stirred; adding ammonium carbonate, calcium hydroxide, pearl powder, Tween 80 and Span 80 into the mixture at the same time, and stirring to obtain emulsion; and pouring the emulsion on a silver wiping cloth, and wiping with the silver wiping cloth to remove color spots. According to the method, the to-be-treated silverware is firstly placed in the organic acid, then ammonium carbonate, calcium hydroxide, pearl powder, Tween 80 and Span 80 are added into the organic acid at the same time, finally wiping is carried out, and color spots on the surface of the silverware are efficiently removed through the sequential adding sequence of the substances, the mutual synergistic effect of the substances and the synergistic effect of chemical removal and physical friction. Meanwhile, the used agent is free of cyanide and toxicity, stable in performance, wide in applicability, convenient to operate and low in cost, the surface of the silverware is not damaged when the agent is used, and the surface of the silverware is bright as new.

Description

Technical Field

[0001] The invention relates to the technical field of silver product processing, and in particular to a method for removing color spots on the surface of silver products. Background Art

[0002] Silver has an attractive white luster, high chemical stability and collection value. It is popular among people and widely used as jewelry, tableware, medals and commemorative coins. Silver jewelry has a broad market in developing countries; silver tableware is popular among families; silver commemorative coins are exquisitely designed, issued in small quantities, and have the function of preserving and increasing value, which are favored by coin collectors and coin investors. However, silver products exposed to the air for a long time are prone to black or yellow spots on the surface, gradually covering the entire surface of the silverware, affecting the beauty and ornamental value of the objects, and greatly reducing their collection value.

[0003] The main component of black or yellow spots on the surface of silverware is silver sulfide, and it also contains components such as silver chloride. The discoloration of silverware affects the appearance and reflective properties of silver products. Therefore, removing color spots on the surface of silver products is an urgent and practical problem that needs to be solved.

[0004] In recent years, many silver surface polishes have been studied at home and abroad. However, some of the polishes contain highly toxic cyanide, which is not only harmful to the environment, but also detrimental to the personal safety of operators. Summary of the invention

[0005] In view of the technical problems existing in the background technology, the present application provides a method for removing color spots on the surface of silverware, aiming to solve the technical problem of the presence of highly toxic cyanide in the current silverware surface brightener.

[0006] The present invention provides a method for removing stains on the surface of silverware, comprising the following steps:

[0007] S1. placing the silverware to be treated in a mixture of organic acid and hydrogen peroxide and stirring;

[0008] S2, then add ammonium carbonate, calcium hydroxide, pearl powder, Tween 80 and Span 80 simultaneously and stir to obtain an emulsion;

[0009] S3, pouring the emulsion onto a silver-polishing cloth, and wiping with the silver-polishing cloth to remove the stains.

[0010] In the technical solution of the embodiment of the present application, the silverware to be treated is first placed in an organic acid to convert the silver sulfide on the surface of the silverware into free silver ions. At the same time, the presence of hydrogen peroxide can further promote the conversion of silver sulfide into free silver ions, providing favorable conditions for the subsequent removal of silver sulfide. Then, ammonium carbonate, calcium hydroxide, pearl powder, Tween 80 and Span 80 are added to the solution at the same time. The ammonia water obtained by the interaction of ammonium carbonate and calcium hydroxide complexes the silver ions to remove the silver sulfide. At the same time, the ammonia water complexes with the silver chloride in the stain to remove it. The calcium carbonate and pearl powder obtained by the interaction of ammonium carbonate and calcium hydroxide cooperate with each other to provide favorable conditions for subsequent wiping. In addition, the Tween 80 and Span 80 with similar structures in the emulsion cooperate with each other to enhance the emulsification effect. At the same time, they also have excellent wetting and washing functions, so that the various substances in the emulsion are better in contact with the silverware to be treated, further promoting the effective removal of the stain, and forming a protective film on the surface of the silverware. Then pour the emulsion onto a silver polishing cloth and use it to wipe the silverware. During this process, on the one hand, the substances in the emulsion further react chemically with the stains to remove the stains; on the other hand, the Mohs hardness of calcium carbonate is similar to that of silver, and the silver polishing cloth can rub against the silverware well during the wiping process. At the same time, the pearl powder can also rub against the silverware, and the pearl powder can also promote the effective friction between calcium carbonate and silverware and ensure that there are no scratches on the surface of the silverware. In addition, Tween 80 and Span 80 can also promote the attachment of pearl powder to the surface of the silverware, improve the brightness of the surface of the silverware, and finally form a bright protective film on the surface of the silverware. Furthermore, chemical removal of stains can also provide a basis for the subsequent physical friction removal of stains. Under the synergistic effect of various substances and chemical removal and physical friction, the stains on the surface of the silverware can be removed efficiently.

[0011] In some embodiments, in step S1, the organic acid is glutamic acid or taurine.

[0012] In this embodiment, glutamic acid or taurine provides specific acidic conditions for the solution, and the presence of hydrogen ions promotes the release of silver ions in silver sulfide; and glutamic acid or taurine is a green agent and is environmentally friendly.

[0013] In some embodiments, the concentration of glutamate or taurine is 10-30 g / L, and the concentration of hydrogen peroxide is 10-30 g / L.

[0014] In this embodiment, glutamic acid or taurine and hydrogen peroxide are controlled within a suitable concentration range, further providing the solution with a suitable concentration of hydrogen ions and an acidic environment, thereby promoting the removal of stains.

[0015] In some embodiments, the concentration of ammonium carbonate is 50-100 / L, the concentration of calcium hydroxide is 50-100 g / L; the concentration of pearl powder is 100-150 g / L; the concentration of Tween 80 is 30-100 g / L, and the concentration of Span 80 is 10-100 g / L.

[0016] In this embodiment, the concentrations of ammonium carbonate, calcium hydroxide, pearl powder, Tween 80 and Span 80 are controlled within a suitable concentration range to effectively remove stains.

[0017] In some embodiments, the pearl powder has a particle size of less than 15 μm.

[0018] In this embodiment, the pearl powder is controlled within a suitable particle size range to promote the synergistic effect of the pearl powder and calcium carbonate to achieve a better stain removal effect.

[0019] In some embodiments, in step S1, the stirring time is 1-3 min, and the stirring speed is 400-600 rpm.

[0020] In some embodiments, in step S2, the stirring time is 3-5 min, and the stirring speed is 400-600 rpm.

[0021] In some embodiments, in step S3, the wiping time is 30-180 seconds.

[0022] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings used in the present application. Obviously, the drawings described below are only some embodiments of the present application, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 This is a picture of the silver sheet with color spots in Examples 1 to 5 of the present application.

[0025] Figure 2 This is a picture of the silver sheet after the color spots are removed in Examples 1 to 5 of the present application. DETAILED DESCRIPTION

[0026] The following embodiments of the technical solution of the present application are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0028] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0029] Silver products that are exposed to the air for a long time are prone to black or yellow spots on the surface. The main component of the black or yellow spots is silver sulfide, and they also contain silver chloride and other components. The spots will gradually cover the entire surface of the silverware, affecting the beauty and ornamental value of the object and greatly reducing its collection value.

[0030] In order to solve the technical problem of the presence of highly toxic cyanide in the currently used brightener, the present application provides a method for removing color spots on the surface of silverware, wherein the silverware to be treated is first placed in an organic acid, and then ammonium carbonate, calcium hydroxide, pearl powder, Tween 80 and Span 80 are added thereto at the same time, and finally wiped, and the color spots on the surface of the silverware are efficiently removed through the order of adding the substances, the mutual synergy between the substances, and the synergy of chemical removal and physical friction. In addition, the agent used in the method of the present invention is cyanide-free and non-toxic, has stable performance, wide applicability, is easy to operate, has low cost, and does not damage the surface of the silverware when used, so that the surface of the silverware is bright as new.

[0031] For the convenience of description, the following embodiments are described by taking a method for removing color spots on the surface of silverware according to an embodiment of the present application as an example.

[0032] The present invention provides a method for removing stains on the surface of silverware, comprising the following steps:

[0033] S1. placing the silverware to be treated in a mixture of organic acid and hydrogen peroxide and stirring;

[0034] S2. Then, ammonium carbonate, calcium hydroxide, pearl powder, Tween 80 and Span 80 are added thereto at the same time and stirred to obtain an emulsion; the main component of Tween 80 is polyoxyethylene sorbitan monooleate, and the main component of Span 80 is sorbitan fatty acid ester.

[0035] S3. Pour the emulsion onto the silver-polishing cloth and wipe it with the cloth to remove stains.

[0036] In the technical solution of the embodiment of the present application, the silverware to be treated is first placed in an organic acid to convert the silver sulfide on the surface of the silverware into free silver ions. At the same time, the presence of hydrogen peroxide can further promote the conversion of silver sulfide into free silver ions, providing favorable conditions for the subsequent removal of silver sulfide. Then, ammonium carbonate, calcium hydroxide, pearl powder, Tween 80 and Span 80 are added to the solution at the same time. The ammonia water obtained by the interaction of ammonium carbonate and calcium hydroxide complexes the silver ions to remove the silver sulfide. At the same time, the ammonia water complexes with the silver chloride in the stain to remove it. The calcium carbonate and pearl powder obtained by the interaction of ammonium carbonate and calcium hydroxide cooperate with each other to provide favorable conditions for subsequent wiping. In addition, the Tween 80 and Span 80 with similar structures in the emulsion cooperate with each other to enhance the emulsification effect. At the same time, they also have excellent wetting and washing functions, so that the various substances in the emulsion are better in contact with the silverware to be treated, further promoting the effective removal of the stain, and forming a protective film on the surface of the silverware. Then pour the emulsion onto a silver polishing cloth and use it to wipe the silverware. During this process, on the one hand, the substances in the emulsion further react chemically with the stains to remove the stains; on the other hand, the Mohs hardness of calcium carbonate is similar to that of silver (silver has a Mohs hardness of 2.5-4.0; calcium carbonate has a Mohs hardness of 3.0). The silver polishing cloth can rub against the silverware well during the wiping process. At the same time, the pearl powder can also rub against the silverware. The pearl powder can also promote the effective friction between calcium carbonate and silverware and ensure that there are no scratches on the surface of the silverware. In addition, Tween 80 and Span 80 can also promote the attachment of pearl powder to the surface of the silverware, improve the brightness of the silverware surface, and finally form a bright protective film on the surface of the silverware. Furthermore, chemical removal of stains can also provide a basis for the subsequent physical friction removal of stains. Under the synergistic effect of various substances and chemical removal and physical friction, the stains on the surface of the silverware can be efficiently removed.

[0037] Furthermore, in some embodiments, in step S1, the organic acid is glutamic acid or taurine.

[0038] In the technical solution of the embodiment of the present application, glutamate or taurine provides specific acidic conditions for the solution, and the presence of hydrogen ions promotes the release of silver ions in silver sulfide; and glutamate or taurine, as green agents, is environmentally friendly.

[0039] Further, in some embodiments, the concentration of glutamate or taurine is 10-30 g / L, and the concentration of hydrogen peroxide is 10-30 g / L.

[0040] In the technical solution of the embodiment of the present application, glutamic acid or taurine and hydrogen peroxide are controlled within a suitable concentration range, further providing the solution with a suitable concentration of hydrogen ions and an acidic environment to promote the removal of stains.

[0041] Further, in some embodiments, the concentration of ammonium carbonate is 50-100 g / L, and the concentration of calcium hydroxide is 50-100 g / L.

[0042] Further, in some embodiments, the concentration of pearl powder is 100-150 g / L.

[0043] Further, in some embodiments, the concentration of Tween 80 is 30-100 g / L, and the concentration of Span 80 is 10-100 g / L.

[0044] In the technical solution of the embodiment of the present application, ammonium carbonate, calcium hydroxide, pearl powder, Tween 80 and Span 80 are controlled within a suitable concentration range to effectively remove stains.

[0045] Furthermore, in some embodiments, the particle size of the pearl powder is less than 15 μm.

[0046] In the technical solution of the embodiment of the present application, the pearl powder is controlled within a suitable particle size range to promote the synergistic effect of the pearl powder and calcium carbonate to achieve a better stain removal effect.

[0047] Furthermore, in some embodiments, in step S1, the stirring time is 1-3 min, and the stirring speed is 400-600 rpm.

[0048] Furthermore, in some embodiments, in step S2, the stirring time is 3-5 min, and the stirring speed is 400-600 rpm.

[0049] Furthermore, in some embodiments, in step S3, the wiping time is 30-180 seconds.

[0050] Some specific embodiments are listed below. It should be noted that the embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. The reagents or instruments used without specifying the manufacturer are all conventional products that can be obtained commercially.

[0051] Example 1

[0052] A method for removing stains on the surface of silverware comprises the following steps:

[0053] S1. Place the silver sheet that has been exposed to the air for a long time in a mixture of glutamic acid and hydrogen peroxide and stir for 3 minutes at a stirring speed of 500 rpm; the concentration of glutamic acid is 20 g / L (i.e., 20 g of glutamic acid is added to 1 L of deionized water), and the concentration of hydrogen peroxide is 20 g / L.

[0054] S2, then add ammonium carbonate, calcium hydroxide, pearl powder, Tween 80 and Span 80 simultaneously and stir for 5 minutes at a stirring speed of 500 rpm to obtain an emulsion, wherein the concentration of ammonium carbonate is 80 g / L, the concentration of calcium hydroxide is 80 g / L, the concentration of pearl powder is 120 g / L, the concentration of Tween 80 is 60 g / L, and the concentration of Span 80 is 50 g / L.

[0055] S3. Pour the above emulsion onto a silver-polishing cloth and wipe it with the cloth for 30 seconds (the wiping time refers to the time taken to remove the stains; if stains remain, the wiping time refers to the time taken for the silver-polishing cloth to wipe the silver sheet; the wiping time is in seconds).

[0056] Examples 2-3 and Comparative Examples 1-2

[0057] A method for removing stains on the surface of silverware, compared with Example 1, the difference is that the concentration of glutamic acid in step S1 is different, and the other steps are substantially the same as Example 1 and will not be repeated here.

[0058] Table 1 Color spot removal effect of Examples 1-3 and Comparative Examples 1-2

[0059] Example Glutamate concentration (g / L) Wiping time(s) Pigmentation Scratches Example 1 20 30 none none Example 2 15 53 none none Example 3 30 55 none none Comparative Example 1 0 308 none have Comparative Example 2 40 60 none none

[0060] It can be seen from the data of Examples 1-3 in Table 1 that within a certain range, as the concentration of glutamic acid continues to increase, the wiping time first decreases and then increases, and there is no color spot on the surface of the silver sheet after wiping, and no scratches are produced during the wiping process. As the concentration of glutamic acid further increases (Comparative Example 2), the wiping time further increases. This may be because the change in glutamic acid concentration affects the acidity, which in turn affects the interaction between each substance and the color spot, affecting the wiping time.

[0061] When glutamic acid is not added (Comparative Example 1), the wiping time is significantly prolonged and scratches are produced. This is mainly because without the addition of glutamic acid, silver sulfide cannot be converted into free silver ions, and chemical spot removal is basically impossible. The spots are mainly removed by physical wiping.

[0062] Examples 4-5 and Comparative Examples 3-4

[0063] A method for removing stains on the surface of silverware, compared with Example 1, the difference is that the concentrations of ammonium carbonate, calcium hydroxide, pearl powder, Tween 80 and Span 80 in step S2 are different, and the rest are substantially the same as Example 1 and will not be repeated here.

[0064] Table 2 Color spot removal effect of Examples 4-5 and Comparative Examples 3-4

[0065]

[0066]

[0067] As can be seen from Table 2, the changes in the concentrations of ammonium carbonate, calcium hydroxide, pearl powder, Tween 80 and Span 80 in step S2 will affect the removal effect of the stains. Only substances in the appropriate concentration range can achieve a better stain removal effect. When the concentration is too low (Comparative Example 3), the wiping time is significantly prolonged. This may be because the changes in the concentrations of ammonium carbonate, calcium hydroxide, pearl powder, Tween 80 and Span 80 affect the mutual coordination of the substances in the process of removing the stains, thereby affecting the stain removal effect. With the further increase in the concentration of each substance (Comparative Example 4), the wiping time remains basically unchanged, but the scratches gradually increase. This may be because the content of calcium carbonate and pearl powder in the emulsion is too high at this time, causing wear to the silver sheet during the wiping process.

[0068] like Figure 1 As shown, the silver flakes with color spots on the surface in Example 1-5 are obtained as shown in Figure 2 The picture of the silver sheet after removing the stains is shown, and there are no scratches on the surface of the silver sheet.

[0069] Example 6

[0070] A method for removing color spots on the surface of silverware, compared with Example 1, the difference is that the organic acid in step S1 is taurine, and the rest is substantially the same as Example 1, which will not be repeated here. The wiping time of Example 6 is 150s, and the color spots are basically completely removed without scratches.

[0071] Comparative Examples 5-14

[0072] A method for removing stains on the surface of silverware, compared with Example 1, the difference is that the concentrations of ammonium carbonate, calcium hydroxide, pearl powder, Tween 80 and Span 80 in step S2 are different, and the total concentration is the same. The rest is substantially the same as Example 1 and will not be repeated here.

[0073] Table 3 Comparative Examples 5-14 Spot Removal Effect

[0074]

[0075]

[0076] It can be seen from Table 3 that when one or more of the substances among ammonium carbonate, calcium hydroxide, pearl powder, Tween 80 and Span 80 are not added, the stain removal effect is poor.

[0077] When ammonium carbonate and calcium hydroxide are not added in Comparative Example 5, color spots still remain even after a long wiping time. This is mainly because the free silver ions and silver chloride cannot be well complexed without the addition of ammonium carbonate and calcium hydroxide, which will also affect the subsequent physical friction process of removing color spots.

[0078] In Comparative Example 6, pearl powder was not added, and the wiping time was increased, and scratches were generated. This was mainly because when pearl powder was not added, the synergy between pearl powder and calcium carbonate could not be achieved, thereby affecting the stain removal effect.

[0079] When Tween 80 or Span 80 is not added in Comparative Examples 7 and 8, the emulsion cannot wet the silver sheet well, and the synergistic effect of various substances is affected, thereby affecting the stain removal effect.

[0080] When two or more substances are not added at the same time, the overall stain removal effect is worse. This is mainly because the mutual synergistic effect between the substances is seriously affected, which makes the stain removal effect poor.

[0081] Comparative Example 15

[0082] A method for removing stains on the surface of silverware, compared with Example 1, the difference is that in step S1, glutamic acid is replaced with lysine, and the rest is substantially the same as Example 1 and will not be repeated here.

[0083] Comparative Example 16

[0084] A method for removing stains on the surface of silverware, compared with Example 1, the difference is that in step S2, the pearl powder is replaced with diatomaceous earth of the same particle size, and the rest is substantially the same as Example 1 and will not be repeated here.

[0085] Comparative Example 17

[0086] A method for removing stains on the surface of silverware, compared with Example 1, the difference is that in step S2, Tween 80 is replaced with Tween 20 (polyoxyethylene sorbitan monolaurate), and the rest is substantially the same as Example 1 and will not be repeated here.

[0087] Comparative Example 18

[0088] A method for removing color spots on the surface of silverware, compared with Example 1, the difference is that in step S2, Span 80 is replaced with Span 20 (sorbitan monolaurate), and the rest is basically the same as Example 1 and will not be repeated here.

[0089] Table 4: Stain removal effect of comparative examples 15-18

[0090] Example Wiping time(s) Pigmentation Scratches Example 1 30 none none Comparative Example 15 180 none none Comparative Example 16 38 none have Comparative Example 17 126 Residue none Comparative Example 18 119 Residue none

[0091] As can be seen from Table 4, in Comparative Example 15, glutamic acid was replaced with lysine, and the stain removal time was longer. This may be because it takes a long time for lysine to convert the stains into free silver ions, and the stain removal effect is poor.

[0092] It can be seen from the data of Comparative Examples 16 and 18 that when pearl powder, Tween 80 or Span 80 are replaced with substances with similar effects, the stains cannot be completely removed or scratches will appear during the removal process, indicating that ammonium carbonate, calcium hydroxide, pearl powder, Tween 80 and Span 80 need to work together to achieve a better stain removal effect.

[0093] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A method for removing stains on the surface of silverware, characterized in that: The steps include: S1. placing the silverware to be treated in a mixture of organic acid and hydrogen peroxide and stirring; S2, then add ammonium carbonate, calcium hydroxide, pearl powder, Tween 80 and Span 80 simultaneously and stir to obtain an emulsion; S3, pouring the emulsion onto a silver-polishing cloth, and wiping with the silver-polishing cloth to remove the stains.

2. The method for removing stains on the surface of silverware according to claim 1, characterized in that: In step S1, the organic acid is glutamic acid or taurine.

3. The method for removing stains on the surface of silverware according to claim 2, characterized in that: The concentration of the glutamic acid or taurine is 10-30 g / L, and the concentration of the hydrogen peroxide is 10-30 g / L.

4. The method for removing stains on the surface of silverware according to claim 1, characterized in that: The concentration of the ammonium carbonate is 50-100 g / L, and the concentration of the calcium hydroxide is 50-100 g / L.

5. The method for removing stains on the surface of silverware according to claim 1, characterized in that: The concentration of the pearl powder is 100-150 g / L.

6. The method for removing stains on the surface of silverware according to claim 1, characterized in that: The concentration of the Tween 80 is 30-100 g / L, and the concentration of the Span 80 is 10-100 g / L.

7. The method for removing stains on the surface of silverware according to claim 1, characterized in that: The particle size of the pearl powder is less than 15 μm.

8. The method for removing stains on the surface of silverware according to claim 1, characterized in that: In step S1, the stirring time is 1-3 min, and the stirring speed is 400-600 rpm.

9. The method for removing stains on the surface of silverware according to claim 1, characterized in that: In step S2, the stirring time is 3-5 min, and the stirring speed is 400-600 rpm.

10. The method for removing stains on the surface of silverware according to claim 1, characterized in that: In step S3, the wiping time is 30-180 seconds.

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