WO2018006276A1

WO2018006276A1 - Long-lasting alkaline etchant, and aluminum material and alkaline etching pre-treatment method thereof

Info

Publication number: WO2018006276A1
Application number: PCT/CN2016/088708
Authority: WO
Inventors: 王饶玲
Original assignee: 深圳市恒兆智科技有限公司
Priority date: 2016-07-05
Filing date: 2016-07-05
Publication date: 2018-01-11

Abstract

A long-lasting alkaline etchant applicable for surface treatment of various aluminum materials or aluminum alloys. The long-lasting alkaline etchant comprises: 20-30 parts by weight of a sodium hyposulfite; 15-30 parts by weight of a gum arabic; 10-20 parts by weight of a sodium triphosphate; 5-10 parts by weight of a sodium tartrate; 5-10 parts by weight of a sodium nitrate; and 1-2 parts by weight of an alkylphenol polyethylene glycol ether. The gum arabic increases the viscosity of a solution, thereby increasing the levelness of the solution. A tartaric acid suppresses hard scaling. The sodium nitrate increases the rate of corrosion. The sodium triphosphate improves a cleaning ability and reduces surface tension. The sodium hyposulfite precipitates a metal ion and removes influence of a contaminant. Further disclosed are an aluminum material alkaline etching pre-treatment method and an aluminum material.

Description

Long life alkali corrosion agent and aluminum material and alkali etching pretreatment method thereof

[0001] The present invention relates to the technical field of metal surface treatment, and in particular to a long-life alkali etchant and aluminum material and an alkali etching pretreatment method thereof.

Background technique

[0002] In order to improve the surface properties or appearance of a product, the surface treatment technology of the workpiece is usually applied. For example, the surface treatment of aluminum, iron and their alloys goes deep into all walks of life. Typically, aluminum is usually anodized, or painted, etc., and the surface of the aluminum is usually pretreated, such as degreasing, degreasing, and alkali etching, prior to these surface treatments. Taking the alkali etching treatment as an example, after the etching treatment, a uniform decorative appearance is produced on the surface of the aluminum workpiece. Mild defects such as roll marks, stretch marks, scratches, and scratches are often removed.

[0003] The conventional alkali etching agent is usually made of sodium carbonate, sodium sulfate, sodium nitrate or the like, and is supplemented with other additive components. The corrosion effect of these alkali etchants is insufficient, and the degree of corrosion is difficult to control, which is not conducive to monitoring the alkali corrosion effect with the ruthenium, resulting in poor reliability of alkali corrosion quality and inconsistent effects. Sodium hydroxide alone is prone to excessive corrosion, many fumes, and the bath is susceptible to aging.

technical problem

[0004] In view of the above, a long-lived alkali-etching agent and an aluminum material and an alkali etching pretreatment method thereof having a good alkali etching effect and being easy to control an alkali corrosion effect and having a long service life of a bath are provided.

Problem solution

Technical solution

[0005] A long-life alkali etchant for alkali etching pretreatment before surface treatment of aluminum, comprising component A and component B, said component B being a solid base, said component A comprising the following weight Parts of the ingredients: 20-30 parts sodium thiosulfate, 15-30 parts gum arabic, 10-20 parts sodium tripolyphosphate, 5-10 parts sodium tartrate, 5-10 parts sodium nitrate, 5-10 parts hydroxide Sodium, 1-2 parts alkylphenol ethoxylate.

[0006] An aluminum alkali etching pretreatment method, comprising the steps of: preparing a long-lived alkali etching agent as described above; adding an alkali etching tank to prepare a growth alkali etchant solution, immersing the aluminum material in the bath liquid; After processing the scheduled time , washed, dried. And an aluminum material, the surface of the aluminum material being treated by an aluminum alkali etching pretreatment method as described above.

Advantageous effects of the invention

Beneficial effect

[0007] In the above-mentioned long-life alkali etching agent and aluminum alkali etching pretreatment method, a combination of the A component and the B component is used, and the A component includes a plurality of components, wherein the gum arabic increases the viscosity of the solution, and increases Solution flattening ability, tartaric acid inhibits hard block scaling, sodium nitrate increases corrosion rate, sodium tripolyphosphate and alkylphenol ethoxylate improve cleaning ability, reduce surface tension, and sodium thiosulfate precipitates metal ions to eliminate impurities. Since component A and component B are separated from each other, the desired components can be added to control the alkali etching effect, which is more convenient and effective.

Embodiments of the invention

The invention will be described in detail below with reference to specific embodiments.

[0009] This embodiment provides a long-life alkali etchant for alkali etching pretreatment before surface treatment of aluminum, which comprises the following components by weight: 20-30 parts of sodium thiosulfate, 15-30 parts of Arabian Gum, 10-20 parts sodium tripolyphosphate, 5-10 parts sodium tartrate, 5-10 parts sodium nitrate, 1-2 parts alkylphenol ethoxylate.

[0010] Specifically, the parts by weight of the sodium thiosulfate are 20-25 parts, preferably, the parts by weight of the gum arabic are 20-25 parts, and the parts by weight of the sodium tripolyphosphate The amount by weight of the sodium tartrate is from 6 to 8 parts, and the parts by weight of the sodium nitrate is from 6 to 8 parts. Further, the long-life alkali etchant further comprises 5-10 parts of sodium hydroxide. Among the above ingredients, gum arabic increases solution viscosity, increases solution flattening ability, tartaric acid inhibits hard block scaling, sodium nitrate increases corrosion rate, sodium tripolyphosphate and alkylphenol ethoxylate improves cleaning ability, reduces surface tension, and thio Sodium sulfate precipitates metal ions to eliminate the effects of impurities.

[0011] Another aspect of the present invention provides an aluminum alkali etching pretreatment method, comprising the following steps: preparing a long-lived alkali etching agent as described above; adding an alkali etching tank to prepare a growth alkali etching solution, The aluminum material is immersed in the bath, and after being treated for a predetermined time, it is washed with water and dried. Among them, the treatment temperature is 40-70 ° C, and the treatment time is 2-20 minutes.

[0012] in the aluminum alkali etching pretreatment process, monitoring the free alkali content and aluminum content of the solution in the tank, and monitoring according to The free alkali content and aluminum content supplement the long-lived alkali etchant or sodium hydroxide. The specific monitoring methods are as follows: Take 5 ml of the bath sample from the alkali etching tank, dilute with 100 ml of water, add a few drops of phenolphthalein indicator, and then neutralize the titration with 0.05 mol/L hydrochloric acid until the color changes from red to colorless. Hydrochloric acid is recorded as a milliliter; then the neutralized sample is immediately added to 5 grams of solid NaF. When the solution is not red within 1 minute after adding the new NaF, the titration reaction is completed, and the acid consumed is b ml. The amount of alkali in the bath and the amount of aluminum dissolved in the bath are calculated as follows: Effective corrosion alkali amount = 1.33 (3a-b) g/L, dissolved aluminum = bg/L. Specifically, the amount of the added alkali amount (sodium hydroxide) or the alkali etchant added in the embodiment depends on the content of aluminum, the content of aluminum is in a different range, the total amount of free alkali and the total amount of the alkali etchant It should be in the following range, as shown in the following table.

[] [Table 1]

[0013] During the process, since the bath is continuously used, the components inside are continuously consumed, and the bath is returned to the normal function by adding. When the amount of alkali is insufficient, the solid sodium hydroxide and the alkali etchant are added to the bath liquid, wherein the alkali etchant is added in an amount such that the added weight of the sodium hydroxide in the bath liquid and the weight of the alkali etchant are added. The ratio is 5-10: 1. In addition, in order to prevent the oil from contaminating the bath, the aluminum material is degreased and degreased before being subjected to alkali etching, and then washed with water. After re-alkaline treatment, rinse with water, dry, and set aside.

[0014] This embodiment also provides an aluminum material, and the surface of the aluminum material is treated by an aluminum alkali etching pretreatment method as described above. The above-mentioned long-life alkali etching agent is widely used in the aluminum processing industry to form desired effects, and can remove some defects of the surface of the aluminum material, and mild defects such as rolling marks, tensile marks, scratches, and scratches are often encountered. All are removed. Matte-free alkali etching is suitable for almost all rolled, stretched, molded and extruded aluminum parts, except for silicon-rich cast aluminum alloys. [0015] Hereinafter, the long-life alkali etching agent and the aluminum alkali etching pretreatment method of the embodiment of the present invention are described by way of specific examples.

Embodiment 1

[0017] The ingredients are first mixed according to the following parts by weight: 20 parts sodium thiosulfate, 15 parts gum arabic, 10 parts sodium tripolyphosphate, 5 parts sodium tartrate, 5 parts sodium nitrate, 1 part alkylphenol polyoxyethylene Ether, prepare 5-10 parts of sodium hydroxide, mix and prepare an alkali etchant for use.

[0018] aluminum alkali etching pretreatment method: 6g / l alkali etching agent is added into the alkali etching tank (Note: alkali etching tank is 60g / l sodium hydroxide solution), adding water to prepare a growing alkali solution, will The aluminum material is immersed in the bath, the temperature is about 50 ° C, the treatment is for 10 minutes, taken out, rinsed with water, and the nitric acid is emitted. (Note: The nitric acid is emitted by immersing the profile in a nitric acid solution having a mass ratio of 10% for one minute to remove the profile. Surface impurities, black ash), rinsed with water, dried for later surface treatment.

[0019] After the above treatment, the appearance of the sand surface is formed on the surface of the aluminum material, and the surface of the aluminum material is uniformly corroded, and there are no traces such as scratches and indentations, and no pitting or corrosion is observed, and the gas during the corrosion process is also greatly reduced. Small, the bath is still active even when used in long turns. The aluminum content can still work up to 140g/l, and the inside of the tank is not easy to crystallize.

[0020] Example 2

[0021] The ingredients are first mixed according to the following parts by weight: 24 parts sodium thiosulfate, 16 parts gum arabic, 12 parts sodium tripolyphosphate, 6 parts sodium tartrate, 6 parts sodium nitrate, 1 part alkylphenol polyoxyethylene Ether, prepare 5-10 parts of sodium hydroxide, mix and prepare an alkali etchant for use.

[0022] aluminum alkali etching pretreatment method: 6g / l alkali etching agent is added into the alkali etching tank (Note: alkali etching tank is 60g / l sodium hydroxide solution), adding water to prepare a growing alkali solution, will The aluminum material is immersed in the bath, the temperature is about 50 ° C, the treatment is for 10 minutes, taken out, rinsed with water, and the nitric acid is emitted. (Note: The nitric acid is emitted by immersing the profile in a nitric acid solution having a mass ratio of 10% for one minute to remove the profile. Surface impurities, black ash), rinsed with water, dried for later surface treatment.

[0023] After the above treatment, the appearance of the sand surface is formed on the surface of the aluminum material, and the surface of the aluminum material is uniformly corroded, and there are no traces such as scratches and indentations, and no pitting or corrosion is observed, and the gas during the corrosion process is also greatly reduced. Small, the bath is still active even when used in long turns. The aluminum content can still work up to 140g/l, and the inside of the tank is not easy to crystallize. [0024] Example 3

[0025] The ingredients are first mixed according to the following parts by weight: 26 parts of sodium thiosulfate, 24 parts of gum arabic, 15 parts of sodium tripolyphosphate, 7 parts of sodium tartrate, 7 parts of sodium nitrate, 1 part of alkylphenol polyoxyethylene Ether, prepare 5-10 parts of sodium hydroxide, mix and prepare an alkali etchant for use.

[0026] Aluminum alkali etching pretreatment method: 7g / l A component is added into the alkali etching tank, and then 70g / l B component is added to prepare a growing alkali etchant solution, the aluminum material is immersed in the bath, The temperature is about 50 ° C, treated for 15 minutes, taken out, rinsed with water, nitrated, water rinsed, and dried for subsequent surface treatment.

[0027] After the above treatment, the appearance of the sand surface is formed on the surface of the aluminum material, and the surface of the aluminum material is uniformly corroded, and there are no marks such as scratches and indentations, and no pitting or corrosion is observed, and the gas during the corrosion process is also greatly reduced. Small, the bath is still active even when used in long turns. The aluminum content can still work up to 140g/l, and the inside of the tank is not easy to crystallize.

Embodiment 4

[0029] The ingredients are first mixed according to the following parts by weight: 30 parts sodium thiosulfate, 30 parts gum arabic, 18 parts sodium tripolyphosphate, 8 parts sodium tartrate, 8 parts sodium nitrate, 2 parts alkylphenol polyoxyethylene Ether, prepare 5-10 parts of sodium hydroxide, mix and prepare an alkali etchant for use.

[0030] Aluminum alkali etching pretreatment method: 7.5g / l A component is added into the alkali etching tank, and then 75g / l B component is added to prepare a growing alkali etchant solution, and the aluminum material is immersed in the bath liquid. The temperature is about 50 ° C, treated for 15 minutes, taken out, rinsed with water, lighted with nitric acid, rinsed with water, dried, ready for subsequent surface treatment.

[0031] After the above treatment, the appearance of the sand surface is formed on the surface of the aluminum material, and the surface of the aluminum material is uniformly corroded, and there are no marks such as scratches and indentations, and no pitting or corrosion is observed, and the gas during the corrosion process is also greatly reduced. Small, the bath is still active even when used in long turns. The aluminum content can still work up to 140g/l, and the inside of the tank is not easy to crystallize.

[0032] It should be noted that the present invention is not limited to the above embodiments, and other changes may be made by those skilled in the art according to the inventive spirit of the present invention, and the changes according to the inventive spirit of the present invention should be It is intended to be included within the scope of the invention as claimed.

Claims

Claim

[Claim 1] A long-life alkali etchant for alkali etching pretreatment before surface treatment of aluminum, comprising the following parts by weight: 20-30 parts of sodium thiosulfate, 15-30 parts of gum arabic, 10-20 parts sodium tripolyphosphate, 5-10 parts sodium tartrate, 5-10 parts sodium nitrate, 1-2 parts alkylphenol polyoxyethylene

[Claim 2] The longevity alkali etchant according to claim 1, wherein the sodium thiosulfate has a weight fraction of 20 to 25 parts.

[Claim 3] The longevity alkali etchant according to claim 1, wherein the gum arabic has a weight fraction of 20-25 parts.

[Claim 4] The longevity alkali etchant according to claim 1, wherein the sodium tripolyphosphate has a weight fraction of 12 to 18 parts.

[Claim 5] The longevity alkali etchant according to claim 1, wherein the sodium tartrate is 6-8 parts by weight.

[Claim 6] The long-life alkali etchant according to claim 1, wherein the sodium nitrate is in an amount of 6-8 parts by weight.

[Claim 7] The longevity alkali etchant according to claim 1, which further comprises 5 to 10 parts of sodium hydroxide.

[Attachment 8] An aluminum alkali etching pretreatment method, comprising the steps of: formulating the long-lived alkali etching agent according to any one of claims 1 to 7, adding an alkali etching tank to prepare a growth alkali etchant; The solution is immersed in the bath, and after being treated for a predetermined period of time, it is washed with water and dried.

[Claim 9] The aluminum alkali etching pretreatment method according to claim 8, wherein in the aluminum alkali etching pretreatment process, the free alkali content and the aluminum content of the solution in the tank are monitored, and according to the monitoring The free alkali content and the aluminum content supplement the long-lived alkali etchant or sodium hydroxide.

[Attachment 10] An aluminum material, characterized in that the surface of the aluminum material is treated by the aluminum alkali etching pretreatment method according to claim 8.