CN112011796A

CN112011796A - Electroplating process for plastic surface

Info

Publication number: CN112011796A
Application number: CN202010773918.5A
Authority: CN
Inventors: 王小锋
Original assignee: Shenzhen Shengli Technology Co ltd
Current assignee: Shenzhen Shengli Technology Co ltd
Priority date: 2020-08-04
Filing date: 2020-08-04
Publication date: 2020-12-01

Abstract

The invention relates to the technical field of electroplating processes, in particular to an electroplating process for a plastic surface, which comprises the following steps: activating, chemically plating copper, carving, plating copper, plating cobalt alloy, plating chromium and drying. In the activating treatment and plating process, specific treatment liquid and electroplating liquid are selected, so that the binding force between the plating layer and the plastic is increased, the phenomena of looseness, bubbling, cracking and the like of the plating layer after electroplating are avoided, the surface durability of the product is prolonged, and the product has excellent comprehensive performances of high temperature resistance, corrosion resistance and the like; meanwhile, the magnetic conductivity is less than 1.1, the resistance value is less than 1.0, and the method can be better applied to electroplating treatment of ABS plastic surfaces of mobile phone and camera frames.

Description

Electroplating process for plastic surface

Technical Field

The invention relates to the technical field of electroplating processes, in particular to an electroplating process for a plastic surface.

Background

Plastic products are more widely used, and because the gloss of the plastic products is lower than that of metal and the decoration effect is relatively poor, people try to have metallic gloss and aesthetic appearance by electroplating the surface of the plastic products and metalizing the surface of the plastic products. In recent years, with the rapid development of the automobile industry, the electrical industry, the household appliances and the ornaments industry, the technology for electroplating metal on the surface of plastic is also continuously developed. The electroplated plastic product integrates the characteristics of plastics and metals, not only has beautiful appearance, but also has greatly improved physical and mechanical properties, and is endowed with new characteristics of electric conduction, magnetic conduction, welding and the like. Therefore, plastic electroplating is now an important process for plastic decoration.

However, in many current electroplating processes, the surface of the plastic is not treated in place before electroplating treatment, so that after electroplating is finished, a plating layer is unstable and uneven, the plating layer has poor deep plating capacity, the plating layer is easy to become brittle, the service life is short, after long-time use, the surface is easy to be seriously abraded, the plastic base color is exposed, the attractiveness is affected, and meanwhile, the bonding force between the plastic and the plating layer is not high, so that the plating layer is easy to generate the problems of foaming, cracking and the like. In addition, the plating layer obtained from the plating solution is also high in resistance value and magnetic permeability during plating, and the use thereof is limited.

Disclosure of Invention

In order to solve the above technical problems, a first aspect of the present invention provides a plastic surface electroplating process, including the following steps: activating, chemically plating copper, carving, plating copper, plating cobalt alloy, plating chromium and drying.

As a preferred technical solution of the present invention, the activation treatment includes coarsening, neutralization, palladium activation, and dispergation.

As a preferred technical solution of the present invention, the palladium activation process is: and (3) feeding the neutralized plastic base material into a palladium activation tank containing a palladium activation solution, wherein the palladium activation temperature is 26-32 ℃, the palladium activation time is 1-6 min, and feeding the treated plastic base material into a cleaning tank for cleaning.

As a preferred technical solution of the present invention, the palladium activation solution is a mixed aqueous solution containing palladium ions, and comprises the following components in concentration: 12-30 ppm of palladium ions, 220-320 ml/L of hydrochloric acid and 2-6 g/L of stannous chloride.

As a preferred technical scheme of the invention, the source of the palladium ions is palladium water or palladium salt; the palladium salt is any one of tetraamminepalladium sulfate, diammine palladium sulfate, tetraamminepalladium chloride, diammine palladium chloride and palladium tetrachloro ammonia.

As a preferred technical solution of the present invention, the electroless copper plating process comprises: and (3) feeding the dispergated plastic substrate into a plating bath containing chemical copper plating solution, wherein the chemical copper plating temperature is 45-58 ℃, and the chemical copper plating time is 2-8 min.

In a preferred embodiment of the present invention, the chemical copper plating solution comprises the following components in concentration: 60-90 ml/L of formaldehyde, 45-75 g/L of copper sulfate, 5-10 g/L of sodium citrate and 2.5-4.5 g/L of sodium gluconate; the pH value of the chemical copper plating solution is 10-11.

As a preferred technical scheme of the invention, the cobalt alloy plating process comprises the following steps: feeding the plastic substrate after copper plating into a plating bath containing cobalt alloy electroplating solution, wherein the current density is 0.2-2A/dm²(ii) a The pH value of the plating solution is 2-3.5, the plating temperature is 55-65 ℃, and the plating time is 10-15 min.

As a preferred embodiment of the present invention, the cobalt alloy electroplating solution comprises the following components: cobalt salt, inorganic acid and salt thereof, and complexing agent.

As a preferable technical scheme of the invention, the cobalt salt is selected from one or a combination of more of cobalt sulfate, basic cobalt carbonate, cobalt sulfamate, cobalt acetate, cobalt methane sulfonate, cobalt chloride, cobalt nitrate and cobalt acetate.

Has the advantages that: the invention provides an electroplating process for a plastic surface, which adopts the working procedures of activation treatment, chemical copper plating, carving, copper plating, cobalt alloy plating, chromium plating and drying, selects specific treatment liquid and electroplating liquid in the activation treatment and plating process, increases the binding force between a plating layer and the plastic, avoids the phenomena of looseness, bubbling, cracking and the like of the plating layer after electroplating, prolongs the surface durability of a product, and has excellent comprehensive performances of high temperature resistance, corrosion resistance and the like; meanwhile, the magnetic conductivity is less than 1.1, the resistance value is less than 1.0, and the method can be better applied to electroplating treatment of ABS plastic surfaces of mobile phone and camera frames.

Detailed Description

The disclosure may be understood more readily by reference to the following detailed description of preferred embodiments of the invention and the examples included therein. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, the present specification, including definitions, will control.

The terms "comprises," "comprising," "includes," "including," "has," "having," "contains," "containing," or any other variation thereof, as used herein, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

When an amount, concentration, or other value or parameter is expressed as a range, preferred range, or as a range of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted to include the ranges "1 to 4", "1 to 3", "1 to 2 and 4 to 5", "1 to 3 and 5", and the like. When a range of values is described herein, unless otherwise stated, the range is intended to include the endpoints thereof and all integers and fractions within the range.

In addition, the indefinite articles "a" and "an" preceding an element or component of the invention are not intended to limit the number requirement (i.e., the number of occurrences) of the element or component. Thus, "a" or "an" should be read to include one or at least one, and the singular form of an element or component also includes the plural unless the number clearly indicates the singular.

In a preferred embodiment, the activation treatment comprises coarsening, neutralization, palladium activation, dispergation.

In one embodiment, the roughening process is: and (3) conveying the plastic substrate into a roughening tank containing roughening liquid, wherein the roughening temperature is 68-73 ℃, the roughening time is 8-15 min, and conveying the treated plastic substrate into a cleaning tank for cleaning.

In a preferred embodiment, the roughening liquid comprises the following components in the following concentrations: chromic anhydride 350-450 g/L and sulfuric acid 350-420 g/L.

In a more preferred embodiment, the roughening liquid comprises the following components in the following concentrations: chromic anhydride 400g/L and sulfuric acid 385 g/L.

In one embodiment, the neutralization process is: and feeding the roughened plastic base material into a neutralizing tank containing a neutralizing solution, wherein the neutralizing temperature is 25 ℃, the neutralizing time is 1-3 min, and feeding the treated plastic base material into a cleaning tank for cleaning.

In a preferred embodiment, the neutralizing solution is a mixed water solution containing chloride ions, and comprises the following components in concentration: 200-400 g/L of chloride ions; the chloride ion source is any one of hydrochloric acid, potassium chloride, lithium chloride, calcium chloride and copper chloride; more preferably, the chloride ion is 300g/L and the source is hydrochloric acid.

In one embodiment, the palladium activation process is: and (3) feeding the neutralized plastic base material into a palladium activation tank containing a palladium activation solution, wherein the palladium activation temperature is 26-32 ℃, the palladium activation time is 1-6 min, and feeding the treated plastic base material into a cleaning tank for cleaning.

In a preferred embodiment, the palladium activation solution is a mixed aqueous solution containing palladium ions, and comprises the following components in concentration: 12-30 ppm of palladium ions, 220-320 ml/L of hydrochloric acid and 2-6 g/L of stannous chloride; the source of the palladium ions is palladium water or palladium salt; the palladium salt is any one of tetraamminepalladium sulfate, diammine palladium sulfate, tetraamminepalladium chloride, diammine palladium chloride and palladium tetrachloro ammonia; more preferably, the palladium activation solution is a mixed aqueous solution containing palladium ions, and comprises the following components in concentration: 21ppm of palladium ions, 270ml/L of hydrochloric acid and 4g/L of stannous chloride; the source of palladium ions is tetraamminepalladium sulfate.

In one embodiment, the dispergation process is: and (3) conveying the plastic base material activated by palladium into a degumming tank containing a degumming solution, wherein the degumming temperature is 35-50 ℃, and the degumming time is 1-4 min.

In a preferred embodiment, the dispergation solution comprises the following components in the following concentrations: 80-100 ml/L of hydrochloric acid; more preferably, the dispergation solution comprises the following components in concentration: hydrochloric acid 90 ml/L.

The roughening solution has strong roughening capacity on the ABS plastic under the action of the roughening solution, and the roughening solution can oxidize butadiene in the ABS or the ABS containing PC to form anchoring points, SO that more hydrophilic polar groups such as C-O, -OH and-SO are generated on the surface of the plastic₃H, -COOH and the like, which greatly improve the hydrophilicity of the plastic surface and are beneficial to chemical bonding, thereby improving the bonding force of the plating layer; the sulfuric acid can react with styrene to increase the bonding force of palladium; but the formed hexavalent chromium is relatively polluted and is relatively harmful to human bodies, and on the basis of the consideration, the reagent containing 200-400 g/L of chloride ions is adopted to neutralize the hexavalent chromium ions at room temperature; the method is matched with a specific palladium activation process, namely, 12-30 ppm of palladium ions, 220-320 mL/L of hydrochloric acid and 2-6 g/L of stannous chloride are adopted to treat a workpiece at 6-32 ℃ for 1-6 min, and particularly when the method is used together with 80-100 mL of hydrochloric acid dispergation liquid, the charged palladium ions and groups on the surface of plastic act to change non-conductive plastic into a conductive surface so as to promote the binding force between the non-conductive plastic and a plating layer, and the stannous ions in a system are beneficial to improving the stability of the palladium ions and avoiding the inactivation of the palladium ions, but not all palladium ions, stannous chloride and hydrochloric acid systems are suitable, and on one hand, the stannous chloride needs to be controlled to be used for controlling the stannous chlorideThe content relationship of hydrochloric acid is that the hydrochloric acid is 220-320 ml/L and the stannous chloride is 2-6 g/L, and when the concentration of the hydrochloric acid in the system is relatively high and the stannous chloride is relatively less, the oxidation degree of the stannous chloride in the system is increased, so that the difficulty in the peptizing process is increased, the aggregation of a glue layer on the surface of the plastic is caused, the formation of a subsequent plating layer is influenced, the problem of plating leakage is caused, and the performance of the plating layer is influenced; but also causes the stability of the system palladium ions to be reduced and the binding force of the plating layer to be reduced; when the content of hydrochloric acid is low, the pH value of the system is increased, the stability of stannous chloride is poor, the stability of palladium ions of the system is reduced, and the binding force of a plating layer is reduced.

In addition, when the concentration of palladium ions in the system is controlled within the range of 12-30 ppm, the obtained plating layer has good binding force and good compactness, and when the concentration of the palladium ions is higher or lower, the properties of the obtained plating layer can be influenced; when the content of the organic acid is less, the activity is lower, and the binding force between the plastic and the coating is reduced.

In one embodiment, the electroless copper plating process is: and (3) feeding the dispergated plastic substrate into a plating bath containing chemical copper plating solution, wherein the chemical copper plating temperature is 45-58 ℃, and the chemical copper plating time is 2-8 min.

In a preferred embodiment, the electroless copper plating solution includes the following concentrations of components: 60-90 ml/L of formaldehyde, 45-75 g/L of copper sulfate, 5-10 g/L of sodium citrate and 2.5-4.5 g/L of sodium gluconate; the electroless copper plating solution has a pH greater than 10.

In a more preferred embodiment, the electroless copper plating solution includes the following concentrations of components: 75ml/L of formaldehyde, 60g/L of copper sulfate, 7g/L of sodium citrate and 3.5g/L of sodium gluconate.

The chemical copper plating is used as an intermediate layer between the plastic and the electroplated layer, has an important effect on the binding force between the finally obtained metal plating layer and the metal, and adopts a plating layer formed by formaldehyde and copper sulfate at the pH value of more than 10, particularly 60-90 ml/L of formaldehyde, 45-75 g/L of copper sulfate, 5-10 g/L of sodium citrate and 2.5-4.5 g/L of sodium gluconate; under the condition of 45-58 ℃, the obtained material has high binding force, and can still keep good binding force under high temperature or ultraviolet irradiation, sodium citrate is probably high in stability and not easy to oxidize, and a complex animal formed by sodium gluconate is stable in structure, so that the complex animal is beneficial to reduction of copper ions at a stable speed under the synergistic action of the complex animal, forms fine-grained sediment, is uniformly deposited on the surface of plastic and forms high binding force with palladium ions, copper powder generated due to reduction of metal copper is avoided, a plating layer is rough, and the binding force is reduced; in addition, when the pH is higher or lower, the deposition rate of copper is higher or the efficiency is lower, resulting in rough plating and poor bonding force, thereby affecting the overall properties of the resulting plating.

In one embodiment, the engraving process is: and forming a pattern on the plastic substrate subjected to electroless copper plating by utilizing laser engraving marks.

In one embodiment, the copper plating process is: the carved plastic substrate is sent into a plating bath containing copper plating solution, the plating voltage is 2-4V, and the plating current density is 0.1-0.3A/dm²The electroplating temperature is 25-35 ℃, and the electroplating time is 5-15 min.

In a preferred embodiment, the copper electroplating bath comprises the following concentrations of components: 150-220 g/L of copper sulfate and 60-80 g/L of sulfuric acid.

In a more preferred embodiment, the copper electroplating bath comprises the following concentrations of components: 185g/L of copper sulfate and 70g/L of sulfuric acid.

In one embodiment, the cobalt alloy plating process is: feeding the plastic substrate after copper plating into a plating bath containing cobalt alloy electroplating solution, wherein the current density is 0.2-2A/dm²(ii) a The pH value of the plating solution is 2-3.5, the plating temperature is 55-65 ℃, and the plating time is 5-15 min.

In a preferred embodiment, the cobalt alloy electroplating bath comprises the following components: cobalt salt, inorganic acid and salt thereof, and complexing agent.

More preferably, the concentration of the cobalt salt is 200-300 g/L; the concentration of the inorganic acid and the salt thereof is 50-130 g/L; the concentration of the complexing agent is 10-40 g/L.

More preferably, the concentration of the cobalt salt is 250 g/L; the concentration of the inorganic acid and the salt thereof is 90 g/L; the concentration of the complexing agent is 25 g/L.

The pH value is 2.0-3.5, the temperature is 55-65 ℃, and the current density is 0.2-2A/dm²The electroplating conditions and the specific electroplating solution have synergistic effect, so that the technical effects of low magnetic permeability and low resistance of the obtained plating layer are realized, the comprehensive performance of the obtained plating layer is good, and when the pH is low or high, the stability of an electroplating solution system can be influenced, the solubility of phosphorus-containing inorganic acid and salt thereof can be influenced, and the deposition of a cobalt complex compound can be influenced, so that the structure of the plating layer is influenced, and the resistance value, the magnetic permeability and the comprehensive performance of the plating layer are influenced; the problem of plating leakage or partial non-plating layer can occur due to low temperature in the electroplating process, and the deposition speed of the plating layer can be accelerated when the temperature is high, so that the refining degree and the dispersion condition of metal can be influenced, and the comprehensive performance is deteriorated.

Cobalt salt

In one embodiment, the cobalt salt is selected from one or more of cobalt sulfate, cobalt carbonate hydroxide, cobalt sulfamate, cobalt acetate, cobalt methane sulfonate, cobalt chloride, cobalt nitrate and cobalt acetate.

In a preferred embodiment, the cobalt salt is cobalt sulfate.

Inorganic acids and salts thereof

In one embodiment, the inorganic acid and salts thereof are phosphorus-containing inorganic acids and salts thereof.

In a preferred embodiment, the phosphorus-containing inorganic acid and its salt are meant to include phosphorus-containing inorganic acids and their corresponding phosphorus-containing inorganic acid salts.

More preferably, the weight ratio of the phosphorus-containing inorganic acid to the phosphorus-containing inorganic acid salt is 1: (1-1.5); more preferably, the weight ratio of the phosphorus-containing inorganic acid to the phosphorus-containing inorganic acid salt is 1: 1.2.

more preferably, the inorganic acid containing phosphorus is selected from one or a combination of several of phosphorous acid, hypophosphorous acid and orthophosphoric acid; more preferably, the phosphorus-containing inorganic acid is phosphorous acid and/or hypophosphorous acid; more preferably, the phosphorus-containing inorganic acid is hypophosphorous acid; more preferably, the phosphorus-containing inorganic acid salt is a hypophosphite salt; more preferably, the hypophosphite salt is sodium/potassium hypophosphite.

Complexing agents

In one embodiment, the complexing agent is an organic acid.

In a preferred embodiment, the organic acid is selected from one or more of citric acid, malic acid, tartaric acid, citric acid, lactic acid, succinic acid, maleic acid, hydroxyethylidene diphosphonic acid and ethylenediamine tetraacetic acid.

More preferably, the organic acid includes citric acid and malic acid.

More preferably, the concentration of the citric acid is 5-15 g/L; the concentration of the malic acid is 5-25 g/L.

More preferably, the concentration of the citric acid is 10g/L citric acid; the concentration of the malic acid is 15 g/L.

The malic acid is D-malic acid (CAS number 636-61-3).

Although the specific phosphorus-containing inorganic acid and the salt thereof are added into the main salt of the cobalt sulfate to be beneficial to reducing the magnetic permeability of the product, the applicant also finds that the reduction degree of the magnetic permeability is variable, the mechanical property, the wear resistance, the corrosion resistance and the like of the obtained plating layer are not ideal, the resistance value of the obtained plating layer is high, and the plating layer is not very suitable for being applied to the formation of the plating layer of a mobile phone camera frame, when citric acid and malic acid are added into the system, particularly when the concentration of the citric acid is 5-15 g/L and the concentration of the malic acid is 5-25 g/L, the obtained plating layer can realize the low magnetic permeability and the low resistance value, the magnetic permeability is less than 1.1 and the resistance value is less than 1.0, and the hardness, the corrosion resistance and the wear resistance of the plating layer are improved, probably because hypophosphorous acid or hypophosphite is oxidized into a phosphorous substance in the system under the condition that the pH is 2, the phosphorous acid substance can keep the valence state and is further complexed with cobalt in the system, but because the solubility of a complex compound in the system is limited, the complex compound is easy to form colloid to be separated out, and simultaneously, the formation of crystal grains of the cobalt is influenced, so that the hardness or compactness of a plating layer is influenced, and even the plating layer is cracked; the malic acid and the citric acid with specific concentration are added into the system to act together, so that a better complex can be formed with cobalt, colloid precipitation is avoided, refinement and reduction of cobalt in a plating layer are promoted, the dispersibility of cobalt and phosphorus in the plating layer is improved, phosphorus content in the plating layer is moderate based on the synergistic effect of phosphorus content with specific content and the malic acid and the citric acid, the great influence of impurities on the resistance of the plating layer is reduced, and the formation of an asymmetric and periodic repetitive structure in the plating layer structure is promoted.

In one embodiment, the chrome plating process is: the plastic base material plated with the cobalt alloy is sent into a plating bath containing chromium plating solution, the plating voltage is 3-5V, and the plating current is 3-5A/dm²The electroplating temperature is 40-60 ℃, and the electroplating time is 5-15 min.

In a preferred embodiment, the chromium electroplating bath comprises the following concentrations of components: 45-65 g/L of trivalent chromium and 40-70 g/L of hydrochloric acid.

In a more preferred embodiment, the chromium electroplating bath comprises the following concentrations of components: 55g/L of trivalent chromium and 55g/L of hydrochloric acid.

In one embodiment, the drying process is: and (3) drying the chromium-plated plastic base material in a drying oven at 35-40 ℃ for 10-30 min to obtain the electroplated plastic workpiece.

When electroplating is performed, carbon, platinum-plated platinum, cobalt, or the like can be used as the anode; the cathode was the target workpiece, which was ABS 920 available from PolyOucan New materials, Inc. of Dongguan.

The solvent of the coarsening solution, the peptizing solution, the chemical copper electroplating solution, the cobalt alloy electroplating solution and the chromium electroplating solution is deionized water.

The second aspect of the invention provides a plastic workpiece prepared by the electroplating process of the plastic surface.

The third aspect of the invention provides an application of the plastic workpiece, which is applied to frames of mobile phones and cameras.

Examples

In order to better understand the above technical solutions, the following detailed descriptions will be provided with reference to specific embodiments. It should be noted that the following examples are only for illustrating the present invention and should not be construed as limiting the scope of the present invention, and that the insubstantial modifications and adaptations of the present invention by those skilled in the art based on the above disclosure are still within the scope of the present invention. In addition, the starting materials used are all commercially available, unless otherwise specified.

Example 1

The embodiment 1 of the invention provides an electroplating process for a plastic surface, which comprises the following steps: activating, chemically plating copper, carving, plating copper, plating cobalt alloy, plating chromium and drying.

The activation treatment comprises coarsening, neutralization, palladium activation and dispergation.

The coarsening process comprises the following steps: and (3) conveying the plastic substrate into a roughening tank containing roughening liquid, wherein the roughening temperature is 70 ℃, the roughening time is 11min, and conveying the treated plastic substrate into a cleaning tank for cleaning.

The coarsening liquid comprises the following components in concentration: chromic anhydride 400g/L and sulfuric acid 385 g/L.

The neutralization process is as follows: and (3) feeding the roughened plastic base material into a neutralizing tank containing a neutralizing solution, wherein the neutralizing temperature is 25 ℃, the neutralizing time is 2min, and feeding the treated plastic base material into a cleaning tank for cleaning.

The neutralizing solution is a mixed water solution containing chloride ions and comprises the following components in concentration: 300g/L of chloride ions; the source of chloride ions is hydrochloric acid.

The palladium activation process is as follows: and (3) feeding the neutralized plastic base material into a palladium activation tank containing a palladium activation solution, wherein the palladium activation temperature is 29 ℃, the palladium activation time is 4min, and feeding the plastic base material into a cleaning tank for cleaning after treatment.

The palladium activating solution is a mixed aqueous solution containing palladium ions and comprises the following components in concentration: 12ppm of palladium ions, 220ml/L of hydrochloric acid and 2g/L of stannous chloride; the source of palladium ions is tetraamminepalladium sulfate.

The degumming process comprises the following steps: and (3) conveying the plastic base material activated by the palladium into a degumming tank containing a degumming solution, wherein the degumming temperature is 42 ℃, and the degumming time is 3 min.

The peptizing solution comprises the following components in concentration: hydrochloric acid 80 ml/L.

The chemical copper plating process comprises the following steps: and (3) conveying the dispergated plastic substrate into a plating tank containing chemical copper plating solution, wherein the chemical copper plating temperature is 51 ℃, and the chemical copper plating time is 5 min.

The electroless copper plating solution includes the following components in concentrations: 60ml/L of formaldehyde, 45g/L of copper sulfate, 5g/L of sodium citrate and 2.5g/L of sodium gluconate.

The copper plating process comprises the following steps: the engraved plastic substrate was placed in a plating bath containing a copper plating solution at a plating voltage of 3V and a plating current density of 0.2A/dm²The electroplating temperature is 30 ℃ and the electroplating time is 10 min.

The copper electroplating solution includes the following components in concentration: 185g/L of copper sulfate and 70g/L of sulfuric acid.

The cobalt alloy plating process comprises the following steps: feeding the plastic substrate plated with copper into a plating bath containing cobalt alloy electroplating solution with a current density of 0.2A/dm²(ii) a The pH value of the plating solution is 2-3.5, the plating temperature is 55 ℃, and the plating time is 10 min.

The current efficiency in the cobalt alloy plating process is 80%.

The cobalt alloy electroplating solution comprises the following components: cobalt salt, inorganic acid and salt thereof, and complexing agent.

The concentration of the cobalt salt is 250 g/L; the concentration of the inorganic acid and the salt thereof is 90 g/L; the concentration of the complexing agent is 25 g/L.

The cobalt salt is cobalt sulfate; the inorganic acid and the salt thereof are phosphorus-containing inorganic acid and the salt thereof; the phosphorus-containing inorganic acid and the salt thereof are phosphorus-containing inorganic acid and the corresponding phosphorus-containing inorganic acid salt; the weight ratio of the phosphorus-containing inorganic acid to the phosphorus-containing inorganic acid salt is 1: 1.2; the phosphorus-containing inorganic acid is hypophosphorous acid; the hypophosphite is sodium hypophosphite.

The complexing agent is organic acid; the organic acid comprises 5g/L citric acid and 5g/L malic acid.

The malic acid is D-malic acid (CAS number 636-61-3).

The chromium plating process comprises the following steps: the plastic base material plated with the cobalt alloy is sent into a plating bath containing chromium plating solution, the plating voltage is 4V, and the plating current is 4A/dm²The electroplating temperature is 50 ℃ and the electroplating time is 10 min.

The chromium electroplating solution comprises the following components in concentration: 55g/L of trivalent chromium and 55g/L of hydrochloric acid.

The drying process comprises the following steps: and (3) placing the chromium-plated plastic base material in a 37 ℃ oven for drying for 20min to obtain the electroplated plastic workpiece.

When electroplating is performed, carbon can be used as an anode; the cathode was the target workpiece, which was ABS 920 available from PolyOucan New materials, Inc. of Dongguan.

Example 2

The embodiment 2 of the invention provides an electroplating process for a plastic surface, which comprises the following steps: activating, chemically plating copper, carving, plating copper, plating cobalt alloy, plating chromium and drying.

The palladium activating solution is a mixed aqueous solution containing palladium ions and comprises the following components in concentration: 30ppm of palladium ions, 320ml/L of hydrochloric acid and 6g/L of stannous chloride; the source of palladium ions is tetraamminepalladium sulfate.

The peptizing solution comprises the following components in concentration: hydrochloric acid 100 ml/L.

The electroless copper plating solution includes the following components in concentrations: 90ml/L of formaldehyde, 75g/L of copper sulfate, 10g/L of sodium citrate and 4.5g/L of sodium gluconate.

Said platingThe cobalt alloy process is as follows: feeding the plastic substrate after copper plating into a plating bath containing cobalt alloy electroplating solution with the current density of 2A/dm²(ii) a The pH value of the plating solution is 2-3.5, the plating temperature is 65 ℃, and the plating time is 10 min.

The current efficiency in the cobalt alloy plating process is 80%.

The complexing agent is organic acid; the organic acid comprises 15g/L of citric acid and 25g/L of malic acid.

The malic acid is D-malic acid (CAS number 636-61-3).

Example 3

Embodiment 3 of the present invention provides a plastic surface electroplating process, including the following steps: activating, chemically plating copper, carving, plating copper, plating cobalt alloy, plating chromium and drying.

The palladium activating solution is a mixed aqueous solution containing palladium ions and comprises the following components in concentration: 21ppm of palladium ions, 270ml/L of hydrochloric acid and 4g/L of stannous chloride; the source of palladium ions is tetraamminepalladium sulfate.

The peptizing solution comprises the following components in concentration: hydrochloric acid 90 ml/L.

The electroless copper plating solution includes the following components in concentrations: 75ml/L of formaldehyde, 60g/L of copper sulfate, 7g/L of sodium citrate and 3.5g/L of sodium gluconate.

The copper plating process comprises the following steps: the carved plastic substrate is sent into a plating bath containing copper electroplating solutionThe plating voltage is 3V and the plating current density is 0.2A/dm²The electroplating temperature is 30 ℃ and the electroplating time is 10 min.

The cobalt alloy plating process comprises the following steps: the plastic substrate after copper plating is sent into a plating bath containing cobalt alloy electroplating solution, and the current density is 1.1A/dm²(ii) a The pH value of the plating solution is 2-3.5, the plating temperature is 60 ℃, and the plating time is 10 min.

The current efficiency in the cobalt alloy plating process is 80%.

The complexing agent is organic acid; the organic acid comprises 10g/L of citric acid and 15g/L of malic acid.

The malic acid is D-malic acid (CAS number 636-61-3).

Comparative example 1

Comparative example 1 of the present invention provides a plating process for a plastic surface, which is similar to example 3, except that the palladium ion concentration of the palladium activation solution is 35 ppm.

Comparative example 2

Comparative example 2 of the present invention provides a plating process for a plastic surface, which is similar to example 3, except that the palladium ion concentration of the palladium activation solution is 9 ppm.

Comparative example 3

Comparative example 3 of the present invention provides a plating process for a plastic surface, which is similar to example 3, except that the palladium activation solution has a hydrochloric acid concentration of 330 ml/L.

Comparative example 4

Comparative example 4 of the present invention provides a plating process for a plastic surface, which is similar to example 3, except that the palladium activation solution has a hydrochloric acid concentration of 210 ml/L.

Comparative example 5

Comparative example 5 of the present invention provides an electroplating process for a plastic surface, which is similar to example 3, except that the palladium activation solution has a stannous chloride concentration of 8 g/L.

Comparative example 6

Comparative example 6 of the present invention provides an electroplating process for a plastic surface, which is similar to example 3, except that the palladium activation solution has a stannous chloride concentration of 1 g/L.

Comparative example 7

Comparative example 7 of the present invention provides a plating process for a plastic surface, which is similar to example 3, except that hydrochloric acid in the peptizing solution is replaced with sodium hydroxide.

Comparative example 8

Comparative example 8 of the present invention provides a plating process for a plastic surface, which is carried out in the same manner as in example 3, except that malic acid is replaced with lactic acid.

Comparative example 9

Comparative example 9 of the present invention provides a plating process for a plastic surface, which is similar to example 4, except that malic acid is replaced with ethylenediaminetetraacetic acid.

Comparative example 10

Comparative example 10 of the present invention provides a process for electroplating a plastic surface, which is similar to example 3, except that malic acid is replaced with ethylenediaminetetraacetic acid.

Comparative example 11

Comparative example 11 of the present invention provides a plating process for a plastic surface, which is similar to example 3, except that the concentration of malic acid is 2 g/L.

Comparative example 12

Comparative example 12 of the present invention provides a plating process for a plastic surface, which is similar to example 3, except that the plating temperature in the cobalt alloy plating process is 75 ℃.

Comparative example 13

Comparative example 13 of the present invention provides a plating process for a plastic surface, which is similar to example 3, except that the plating temperature in the cobalt alloy plating process is 45 ℃.

Comparative example 14

Comparative example 14 of the present invention provides a process for electroplating a plastic surface, which is carried out in the same manner as in example 3, except that sodium citrate in the chemical copper plating solution is replaced with citric acid.

Comparative example 15

Comparative example 15 of the present invention provides a plastic surface electroplating process, which is similar to example 3 in specific embodiment, except that sodium gluconate in the electroless copper plating solution is replaced with malic acid.

Comparative example 16

Comparative example 16 of the present invention provides a plastic surface electroplating process, which is similar to example 3 in specific embodiment, except that sodium gluconate in the chemical copper electroplating solution is replaced with sodium tartrate.

Performance testing

Carrying out the following performance tests 1-13 on the electroplated plastic workpiece samples prepared in the above examples 1-3; carrying out the following performance tests 1, 2, 5, 6 and 8-10 on the electroplated plastic workpiece samples prepared in the comparative examples 1-7 and the comparative examples 12-16; the performance tests 11-12 below were performed on the samples of the electroplated plastic workpieces prepared in comparative examples 8-13. Appearance no anomaly in the following tests means: no discoloration, no bubbling, no cracking, no corrosion, no delamination and no shedding; otherwise, recording an exception.

1. Pencil hardness test

Marking 3 lines with the length of 1.0 +/-0.2 cm on the surface of a sample from different directions at an angle of 45 degrees under the load of 500gf by using a Mitsubishi pencil (UNI series), wiping off the trace of the pencil by using an eraser, sequentially testing from hard to soft from the hardest pencil until a pencil with a coating which is not scratched is found, and recording the hardness value at the moment, wherein the hardness value is A above 7H, B above 5-7H, C below 4-5H (excluding 5H), and D below 4H.

2. Rubber rub test

A500 g load was applied to the sample and a special rubber was used to rub the surface of the material back and forth for 200 cycles. The lateral edges are subjected to 100 cycles, wherein 45 +/-5 times per minute and 20mm of stroke are carried out, the rubber cannot be separated from the sample, the rubber is exposed by 30-40% when the rubber moves to two ends in the small product stroke, and whether the plating layer falls off or not and whether the substrate texture is exposed or not are observed and recorded; wherein, the texture of the coating at the wear-resistant part which does not fall off and expose the substrate is recorded as qualified, otherwise, the coating is unqualified; 10 parallel samples were set and the number was recorded as acceptable.

3. Hexavalent chromium test

Taking 150mL of a proper amount of purified water by using a beaker, taking 12pcs of a product (a sample needs to peel apart TPU and ABS electroplated parts), and simultaneously placing the TPU and the ABS electroplated parts in the beaker; boiling the solution until the volume of the solution is more than 30mL and less than or equal to 50mL, if the volume of the solution is less than 50m, adding purified water to 50mL, and pouring the solution into a color developing bottle with the scale mark on the color developing bottle as the standard (about 15 mL); a small amount of reagent medicine (uniformly using water quality rapid test reagent produced by Guangdong Huanji Microbiol. Tech Co., Ltd.) is taken out from the hexavalent chromium determination kit and added into the color developing bottle, and then the bottle cap is covered and shaken up until the medicine is completely dissolved (the test only aims at plating a side key). After standing for about 10 minutes, taking out the chromium colorimetric card from the hexavalent chromium determination kit, and comparing the color of the solution in the color developing bottle with the color of the solution in the color developing bottle. If the solution in the color developing bottle is colorless and transparent, the sample to be detected does not contain hexavalent chromium; if the solution in the color developing bottle is red, indicating that the sample to be detected contains hexavalent chromium; and marking that the alloy is qualified if the alloy does not contain hexavalent chromium, otherwise, the alloy is unqualified.

4. Alcohol resistance test

Rubbing the sample surface with 99.8% absolute ethanol under 500g pressure at 50 + -5 times/min for 200 times while keeping the flannel moist; observing whether the film is decolorized, falls off or shows the phenomenon of exposing the substrate; wherein, the base material without decolorization, falling off and exposure is marked as qualified, otherwise, the base material is marked as unqualified; 10 parallel samples were set and the number was recorded as acceptable.

5. Salt spray test

Using a NaCl solution with the pH value of 6.5-7.2 and the concentration of 5 wt%, the temperature of a test groove is 33-37 ℃, the test time is 96h, cleaning with clear water after the test, and drying at 50-60 ℃; the coating adhesion was tested using 3M610 gummed paper, where no appearance abnormality and adhesion above 3B was designated A, no appearance abnormality and adhesion between 2B and 3B was designated B, appearance abnormality or adhesion between 1B and 2B (excluding 2B) was designated C, and appearance abnormality or adhesion below 1B was designated D.

6. High temperature storage test

Standing at 73-77 ℃ for 48h, standing at normal temperature for at least 2h, and observing the appearance, wherein no abnormal appearance is recorded as qualified, and abnormal appearance is recorded as unqualified; 10 parallel samples were set and the number was recorded as acceptable.

7. Cosmetic resistance test

The surface of the product is wiped clean by cotton cloth, and cosmetics are uniformly coated on the surface of the sample, wherein each cosmetic is coated with 2 samples. The cosmetics are as follows: nivea sunscreen SPF30PA + +; nivea hand cream; q1a yulan oil sun SPF15PA +; d. liushen mosquito-repellent toilet water; e. baique Ling olive essential oil. Temperature: 55. + -.1 ℃ humidity: 93% -95% RH; time: 48H; after at least 2H is recovered at normal temperature, checking whether the surface of the sample is foamed or not, whether a paint film is obviously abnormal such as falling, separation and the like or not, whether a material is cracked or not and whether the appearance of a product is abnormally changed or not; wherein, the sample surface has no bubble, the paint film has no drop, no separation, no cracking of the material, no abnormal change of the appearance is marked as qualified, otherwise, the sample surface is marked as unqualified; 10 parallel samples were set and the number was recorded as acceptable.

8. Artificial sweat resistance test

Preparing a solution according to an artificial juice preparation instruction, wherein the pH value is 4.6 +/-0.1; the dust-free cloth for soaking the solution is stuck on the surface of the sample and sealed in a constant temperature and humidity box by a sealing rubber bag; temperature: 55. + -.2 ℃ humidity: 93 plus or minus 2 percent; storage time: 48 h; after the test, wiping the solution on the surface of the product, standing for at least 2h at room temperature, observing the appearance, and carrying out an adhesion test; wherein, no bubble, no plating corrosion, no paint film falling, no separation, no black spot with the diameter less than 0.5mm on the silver edge, no flake black block on the silver edge are marked as qualified, otherwise, the silver edge is marked as unqualified; 10 parallel samples were set and the number was recorded as acceptable.

9. Temperature impact resistance test

Keeping at-40 deg.C + -2 deg.C for 1h, and transferring to 75 deg.C + -2 deg.C within 1min and keeping for 1 h; the samples were tested for 20 cycles for 40 h; after the test, the sample is kept stand at normal temperature for at least 2h, and then the appearance is observed, and the adhesive force is tested; directly sticking the plastic water electroplated part on the surface of the sample crystal by using a 3M610 adhesive tape for 3 times without marking grids; wherein, the appearance is not abnormal and the adhesive force is more than 3B and is marked as A, the appearance is not abnormal and the adhesive force is 2B to 3B and is marked as B, the appearance is abnormal or the adhesive force is 1B to 2B (excluding 2B) and is marked as C, and the appearance is abnormal or the adhesive force is less than 1B and is marked as D.

10. Ultraviolet aging test

Sticking black gummed paper or wrapping the non-irradiated surface of the sample by a dark thick paperboard; setting the power of the lamp tube to be 0.63W/m2, placing a sample into a test box, directly irradiating ultraviolet rays on the surface of the paint for 4 hours at the temperature of 60 ℃, then condensing for 4 hours at the temperature of 50 ℃, wherein the cycle is one cycle, taking out the sample after 12 cycles (96 hours), cooling for at least 2 hours at normal temperature, and then inspecting the surface of the paint; the paint surface is not faded, discolored, grains, cracked or peeled, the adhesive force is more than 3B and is marked as A, the paint surface is not faded, discolored, grains, cracked or peeled, the adhesive force is 2B-3B and is marked as B, the paint surface is faded, discolored, grains, cracked or peeled, the adhesive force is less than 1B-2B (excluding 2B) and is marked as C, and the paint surface is faded, discolored, grains, cracked, peeled or adhered, the adhesive force is less than 1B and is marked as D.

11. Permeability test

And testing the magnetic permeability of the sample by using an inductance test, wherein the magnetic permeability is less than Q and not equal to 1.01 and is recorded as A, the magnetic permeability is 1.01-1.1 and is recorded as B, the magnetic permeability is 1.1-1.6 and is recorded as C, and the magnetic permeability is more than 1.6 and is recorded as D.

12. Resistance value test

And (3) performing a resistance value test on the sample according to GB/T6146-2010, wherein the resistance value is less than 1 omega and is recorded as A, the resistance value is 1-1.5 omega and is recorded as B, the resistance value is 1.5-2 omega and is recorded as B, and the resistance value is more than 2 omega and is recorded as C.

TABLE 1

	Example 1	Example 2	Example 3
				Hardness of pencil	A	A	A
Rubber friction	8	8	8
				Hexavalent chromium	Qualified	Qualified	Qualified
Alcohol resistance	10	10	10
				Salt fog	A	A	A
High temperature storage	10	10	10
				Cosmetic product	10	10	10
Artificial sweat resistance water	10	10	10
				Temperature shock resistance	A	A	A
Ultraviolet aging	A	A	A
				Magnetic permeability	A	A	A
Resistance value	A	A	A

TABLE 2

TABLE 3

	Magnetic permeability	Resistance value
			Comparative example 8	C	C
Comparative example 9	C	C
			Comparative example 10	C	C
Comparative example 11	C	C
			Comparative example 12	C	C
Comparative example 13	D	D

The data in the table show that the invention provides the electroplating process for the plastic surface, and the plating layer prepared by the process has good binding force with the plastic, and has excellent comprehensive properties such as high temperature resistance and corrosion resistance; meanwhile, the magnetic conductivity is less than 1.1, the resistance value is less than 1.0, and the method can be better applied to electroplating treatment of ABS plastic surfaces of mobile phone and camera frames.

The foregoing examples are merely illustrative and serve to explain some of the features of the method of the present invention. The appended claims are intended to claim as broad a scope as is contemplated, and the examples presented herein are merely illustrative of selected implementations in accordance with all possible combinations of examples. Accordingly, it is applicants' intention that the appended claims are not to be limited by the choice of examples illustrating features of the invention. Also, where numerical ranges are used in the claims, subranges therein are included, and variations in these ranges are also to be construed as possible being covered by the appended claims.

Claims

1. An electroplating process for a plastic surface is characterized by comprising the following steps: activating, chemically plating copper, carving, plating copper, plating cobalt alloy, plating chromium and drying.

2. The process of claim 1, wherein the activating treatment comprises roughening, neutralizing, palladium activating, and disperging.

3. A process according to claim 2, wherein the palladium activation process is: and (3) feeding the neutralized plastic base material into a palladium activation tank containing a palladium activation solution, wherein the palladium activation temperature is 26-32 ℃, the palladium activation time is 1-6 min, and feeding the treated plastic base material into a cleaning tank for cleaning.

4. A process according to claim 3, wherein the palladium activation solution is a mixed aqueous solution containing palladium ions, and comprises the following components in concentration: 12-30 ppm of palladium ions, 220-320 ml/L of hydrochloric acid and 2-6 g/L of stannous chloride.

5. A process according to claim 4, wherein the source of palladium ions is palladium water or palladium salt; the palladium salt is any one of tetraamminepalladium sulfate, diammine palladium sulfate, tetraamminepalladium chloride, diammine palladium chloride and palladium tetrachloro ammonia.

6. A process for electroplating a plastic surface according to claim 1 or 2, wherein the electroless copper plating process comprises: and (3) feeding the dispergated plastic substrate into a plating bath containing chemical copper plating solution, wherein the chemical copper plating temperature is 45-58 ℃, and the chemical copper plating time is 2-8 min.

7. A process for electroplating a plastic surface according to claim 6, wherein the electroless copper plating solution comprises the following components in the following concentrations: 60-90 ml/L of formaldehyde, 45-75 g/L of copper sulfate, 5-10 g/L of sodium citrate and 2.5-4.5 g/L of sodium gluconate; the pH value of the chemical copper plating solution is 10-11.

8. The electroplating process for the plastic surface as claimed in claim 1, wherein the cobalt alloy plating process comprises the following steps: feeding the plastic substrate after copper plating into a plating bath containing cobalt alloy electroplating solution, wherein the current density is 0.2-2A/dm²(ii) a The pH value of the plating solution is 2-3.5, the plating temperature is 55-65 ℃, and the plating time is 10-15 min.

9. A process for electroplating a plastic surface according to claim 8, wherein the cobalt alloy electroplating solution comprises the following components: cobalt salt, inorganic acid and salt thereof, and complexing agent.

10. A process according to claim 9, wherein said cobalt salt is selected from the group consisting of cobalt sulfate, cobalt carbonate hydroxide, cobalt sulfamate, cobalt acetate, cobalt methanesulfonate, cobalt chloride, cobalt nitrate, and cobalt acetate.