A brightener for mirror polishing of zinc alloy workpieces and methods of making and using

Abstract

The application is suitable for the technical field of brightener, and provides a brightener for mirror polishing of zinc alloy workpieces and a preparation and use method thereof.The brightener comprises the following raw materials in percentage by weight: dimethyl silicone oil emulsion 7-9%, isomeric alcohol polyoxyethylene ether 6-10%, polydiethylene glycol-600 (PEG-600) 3-7%, fatty alcohol polyoxyethylene ether-9 (AEO-9) 4-8%, triethanolamine 1-3%, citric acid monohydrate 1-2%, isothiazolinone preservative 0.05-0.1%, and deionized water, and the rest is supplemented to 100%. Through precise synergy of specific components and concentrations and combined with a unique thermal activation process, the application aims to achieve a "mirror polishing" effect with glossiness ≥95Gs (60°), smooth hand feeling, and first-time qualified rate ≥95%, and meanwhile, the application has the advantages of stable formula, wide process window, and easy scale production.

Description

Technical Field

[0001] This invention belongs to the field of brightener technology, and particularly relates to a brightener for mirror polishing of zinc alloy workpieces and its preparation and application methods. Background Technology

[0002] Zinc alloys are widely used in decorative accessories (such as lobster buckles, zipper pulls, and signs) in industries such as clothing, bags, electronics, and hardware due to their excellent formability, dimensional stability, and surface treatment properties. To enhance product value and aesthetics, their surfaces require mirror polishing. A common process is "tumble polishing," which involves placing the workpiece, abrasive, brightener, and water together in a tumbler. Through mechanical friction and chemical action, the surface smoothness and gloss are improved. The performance of the brightener directly determines the final polishing effect.

[0003] A typical formulation of general-purpose drum polishing brightener usually includes: inorganic or organic acids (to provide an acidic micro-etching environment), anionic or nonionic surfactants (for wetting and cleaning), and a small amount of mineral oil or synthetic wax (to provide basic gloss). When using it, at room temperature (about 15-30℃), it is mixed with water and abrasive in a certain proportion (usually 2-5% of the total working fluid) and then directly loaded into the drum for polishing. Its effect mainly depends on the physical cutting of the abrasive and the slight chemical corrosion of the surface by the acid.

[0004] However, most current brighteners have the following drawbacks:

[0005] Low upper limit of effect: Due to the limitations of the formula principle (physical grinding + micro-etching), its gloss is usually difficult to exceed 90Gs (60°), and because it fails to form a continuous mirror protective film, the workpiece feels dry and lacks the high-end feel of "oily" and "black gloss", which is different from the demand of the high-end market.

[0006] High operational risk: In order to obtain a certain gloss at room temperature, it is often necessary to add strong acidic substances. If the concentration or time is not properly controlled, it is easy to over-corrode the zinc alloy matrix, resulting in workpiece dimensional deviation, surface blackening or corrosion pitting.

[0007] Unstable first-pass yield: Due to the lack of precise control over the core film-forming substances and the high dependence on the operator's experience (such as adding brighteners by feel or judging the endpoint by experience), the consistency of finished products is poor and the rework rate is high (usually the first-pass yield is only 70-85%), which significantly increases production costs and delivery cycle. Summary of the Invention

[0008] The purpose of this invention is to provide a brightener for mirror polishing of zinc alloy workpieces, as well as its preparation and application method, in order to solve the problems mentioned in the background art.

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] On one hand, a brightener for mirror polishing of zinc alloy workpieces comprises the following raw materials by weight percentage: 7-9% dimethyl silicone oil emulsion, 6-10% isomeric alcohol polyoxyethylene ether, 3-7% polyethylene glycol-600 (PEG-600), 4-8% fatty alcohol polyoxyethylene ether-9 (AEO-9), 1-3% triethanolamine, 1-2% citric acid monohydrate, 0.05-0.1% isothiazolinone preservative, and deionized water to make up to 100%.

[0011] On the other hand, a method for preparing a brightening agent for mirror polishing of zinc alloy workpieces includes the following steps:

[0012] Add citric acid monohydrate, triethanolamine, fatty alcohol polyoxyethylene ether-9, isomeric alcohol polyoxyethylene ether, and polyethylene glycol-600 sequentially to deionized water, stir to dissolve, then slowly add dimethyl silicone oil emulsion while stirring at low speed, and finally add isothiazolinone preservatives, adjust the pH, and cool to room temperature for storage.

[0013] On the other hand, a method for using a brightener for mirror polishing of zinc alloy workpieces includes the following steps:

[0014] Add diamond abrasive, workpiece, brightener and deionized water into the drum, submerge the abrasive in the liquid, control the polishing temperature at 40-45℃, the rotation speed at 35-40rpm, and polish for 2-3 hours.

[0015] After polishing, rinse quickly with deionized water 1-2 times and dry at 60-70℃ for 5-10 minutes.

[0016] Compared with the prior art, the specific beneficial effects of the present invention are as follows:

[0017] This invention selects dimethyl silicone oil emulsion as the core brightening component, which forms a dense and continuous mirror molecular film under thermal activation conditions, directly determining the gloss and feel. Isomeric alcohol polyoxyethylene ether is used as the core brightening auxiliary agent, which has the characteristics of low foaming and high penetration, assisting the silicone oil emulsion to spread, filling micropores, and improving reflectivity. Polyethylene glycol-600 is used as a leveling brightening agent to improve film uniformity, enhance "black brightness", and prevent fogging. Fatty alcohol polyoxyethylene ether-9 is used as a wetting and dispersing agent to reduce surface tension and ensure that the brightener evenly covers the workpiece. Triethanolamine and citric acid form a buffer system to stabilize the pH value and ensure the long-term stability of the silicone oil emulsion.

[0018] This invention is based on the synergistic effect of "chemical film formation" and "thermal activation," unlike conventional brighteners that rely on physical grinding and chemical corrosion. It uses a non-ionic dimethyl silicone oil emulsion that is thermally activated at 40-45℃ as the core for mirror film formation. At this temperature, the thermal motion of silicone oil molecules is intensified. With the synergistic effect of wetting agent (AEO-9) and brightening agent (TO-8 / XL-80), it can quickly spread and level on the zinc alloy surface to form a continuous, dense, and highly reflective molecular film, thereby achieving the dual effects of "mirror shine" and "silky smooth feel."

[0019] By precisely synergizing specific components and concentrations, combined with an original thermal activation process, the aim is to achieve a "mirror-like" effect with a gloss level of ≥95Gs (60°), a silky feel, and a first-pass yield of ≥95%. It also has the advantages of stable formula, wide process window, and easy mass production. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0021] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0022] Example 1: A brightener for mirror polishing of zinc alloy workpieces, the preparation method of which includes the following steps:

[0023] Based on a total weight of 1000g, take 690g of deionized water, heat it to 45℃, and add the following raw materials in sequence and stir to dissolve: 15g of citric acid monohydrate, 20g of triethanolamine, 60g of AEO-9, 80g of TO-8, and 50g of PEG-600. While stirring at low speed (300-500rpm), slowly add 80g of dimethyl silicone oil emulsion (50% non-ionic) over 3-5 minutes, continue stirring for 5 minutes until uniform, and finally add 5g of preservative and stir for 3 minutes. The actual pH is 6.0, and the brightener preparation is complete.

[0024] Application Example 1: A method for using a brightener for mirror polishing of zinc alloy workpieces, comprising the following steps:

[0025] In a 200kg octagonal roller, 110kg of diamond abrasive, 40kg of zinc alloy lobster buckles (approximately 120,000 pieces), 7kg of the brightener prepared in Example 1, and 43kg of deionized water were added. The roller speed was controlled at 35-40 rpm, and the temperature was strictly controlled at 42±2℃. Polishing was carried out for 2.5 hours. After completion, the roller was rinsed twice with deionized water (30 seconds each time) and dried at 65℃ for 8 minutes. Sampling test: the average gloss (60°) was 97.2 Gs, the surface felt silky smooth, and there was no haze, scratches, or watermarks on the surface. The first-pass yield was 97%.

[0026] Example 2: A brightener for mirror polishing of zinc alloy workpieces, the preparation method of which includes the following steps:

[0027] Based on a total weight of 1000g, take 720g of deionized water, heat it to 45℃, and add the following raw materials in sequence and stir to dissolve: 5g of triethanolamine, 60g of AEO-9, 80g of TO-8, and 50g of PEG-600. While stirring at low speed, slowly add 80g of dimethyl silicone oil emulsion (50% non-ionic type), and finally add 5g of preservative. The actual pH was measured to be 6.8.

[0028] The difference between Application Example 2 and Application Example 1 is that the brightener prepared in Example 2 has the same effect as that in Example 1 (gloss 96.5Gs). However, since the formulation of Example 2 lacks a buffer system, the brightener must be used up on the same day, and its long-term storage stability is not as good as that of Example 1.

[0029] Comparative Example 1: Zinc alloy brightening agent BZ-808 from Dongguan Baozhen Grinding Machinery Co., Ltd. was used. The process recommended by the manufacturer was as follows: room temperature (25℃), working solution concentration 3%, diamond abrasive 110kg, workpiece 40kg, water 43kg, polishing for 2.5 hours, followed by rinsing and drying after discharge. Test results: gloss (60°) average value 86.3Gs, slightly rough to the touch, surface reflection dispersed, no mirror effect.

[0030] Comparative Example 2: Zinc alloy brightener 802 from Changping Polishing Equipment Co., Ltd. in Yiwu City, Zhejiang Province, was used for drum polishing of zinc alloy lobster buckles. The polishing process parameters were as follows: octagonal drum capacity: 200 kg, diamond spherical abrasive: 110 kg, zinc alloy lobster buckles: 40 kg (approximately 120,000 pieces), brightener addition: 3% of the total working fluid volume, i.e., when the total working fluid volume is 50 kg, 1.5 kg of brightener is added, 48.5 kg of deionized water, water quality: deionized water (TDS < 50 ppm), polishing temperature: room temperature (25℃), polishing time: 2.5 hours, drum speed: 35-40 rpm, post-treatment: after polishing, the workpiece was rinsed twice with deionized water (30 seconds each time) and dried at 65℃ for 8 minutes. Test results: average gloss (60°) 83.1 Gs, rough feel, slight scratches on the surface, first pass rate approximately 85%.

[0031] Performance testing:

[0032] 1. Comparing the effects of Application Example 1 and Comparative Examples 1-2, the results are shown in Table 1:

[0033] Table 1

[0034]

[0035] It can be seen that a complete mirror film can be formed on the sample surface through the synergistic effect of a specific concentration (8%) of nonionic silicone oil emulsion and thermal activation at 40-45℃.

[0036] 2. Stability tests were conducted on the brightener prepared in Example 1 and the brighteners in Comparative Examples 1 and 2. The tests showed that the brightener in Example 1, after being stored at room temperature in a sealed container for 6 months, had a uniform appearance, no layering or precipitation, and a pH fluctuation of ≤0.2. In contrast, Comparative Examples 1 and 2 showed obvious layering or precipitation under the same conditions. This is because the non-ionic system and the citrate-triethanolamine buffer pair strictly controlled the pH at 5.5-6.5, ensuring the long-term stability of the silicone oil emulsion.

[0037] 3. The effect of silicone oil concentration on brighteners:

[0038] With the amounts of citric acid, triethanolamine, AEO-9, TO-8 / XL-80, PEG-600, and preservatives kept constant, only the weight percentages of dimethyl silicone oil emulsion (50% solids content, nonionic, water-based) were adjusted to 6%, 7%, 9%, and 10%, respectively. The amount of deionized water was also adjusted accordingly to balance to 100% of the total mass. A brightener was prepared according to this ratio and polished using the same process parameters as in Application Example 1. The results are shown in Table 2.

[0039] Table 2

[0040]

[0041] It can be seen that when the addition amount is 8%, the gloss, feel and first pass rate are all optimal, and there are no undesirable phenomena such as stickiness or haziness. When the addition amount exceeds 8%, the first pass rate drops significantly, and the problems of stickiness and haziness become apparent.

[0042] In summary, the brightener prepared in this embodiment of the invention is suitable for the polishing process of an octagonal roller + diamond spherical abrasive, and can stably achieve a mirror-like bright surface (gloss level 95-98 Gs), a black and clear appearance, and a silky smooth surface without any defects such as fogging, scratches, or emulsion separation. The success rate of mass production in one go is over 95%, which is significantly better than commercially available products. It is easy to operate, highly stable, and can be directly adapted to long-term industrial mass production, combining technological advancement with industrial practicality.

[0043] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A brightening agent for mirror polishing of zinc alloy workpieces, characterized in that, The raw materials include the following weight percentages: dimethyl silicone oil emulsion 7-9%, isomeric alcohol polyoxyethylene ether 6-10%, polyethylene glycol-600 3-7%, fatty alcohol polyoxyethylene ether-94-8%, triethanolamine 1-3%, citric acid monohydrate 1-2%, isothiazolinone preservatives 0.05-0.1%, and deionized water to make up to 100%.

2. The brightening agent for mirror polishing of zinc alloy workpieces according to claim 1, characterized in that, The ingredients include the following weight percentages: 8% dimethyl silicone oil emulsion, 8% isomeric alcohol polyoxyethylene ether, 5% polyethylene glycol-600, 6% fatty alcohol polyoxyethylene ether-9, 2% triethanolamine, 1.5% citric acid monohydrate, 0.05% isothiazolinone preservatives, and deionized water to make up to 100%.

3. The brightening agent for mirror polishing of zinc alloy workpieces according to claim 1 or 2, characterized in that, The dimethyl silicone oil emulsion is non-ionic and has a solid content of 50%.

4. The brightening agent for mirror polishing of zinc alloy workpieces according to claim 1 or 2, characterized in that, The isomeric alcohol polyoxyethylene ether is TO-8 or XL-80.

5. A method for preparing a brightening agent for mirror polishing of zinc alloy workpieces as described in claim 1, characterized in that, Includes the following steps: Add citric acid monohydrate, triethanolamine, fatty alcohol polyoxyethylene ether-9, isomeric alcohol polyoxyethylene ether, and polyethylene glycol-600 sequentially to deionized water, stir to dissolve, then slowly add dimethyl silicone oil emulsion while stirring at low speed, and finally add isothiazolinone preservatives, adjust the pH, and cool to room temperature for storage.

6. The method for preparing the brightening agent for mirror polishing of zinc alloy workpieces according to claim 5, characterized in that, The step to adjust the pH is to adjust it to 5.5-6.

5.

7. A method of using the brightener for mirror polishing of zinc alloy workpieces as described in claim 1, characterized in that, Includes the following steps: Add diamond abrasive, workpiece, brightener and deionized water into the drum, submerge the abrasive in the liquid, control the polishing temperature at 40-45℃, the rotation speed at 35-40rpm, and polish for 2-3 hours. After polishing, rinse quickly with deionized water 1-2 times and dry at 60-70℃ for 5-10 minutes.

8. The method of using the brightener for mirror polishing of zinc alloy workpieces according to claim 7, characterized in that, The mass ratio of the diamond abrasive, the workpiece, the brightener, and the deionized water is 110:40:7:43.

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