CN107354460B

CN107354460B - Surface treatment liquid for integrated forming of stainless steel and plastic

Info

Publication number: CN107354460B
Application number: CN201710441803.4A
Authority: CN
Inventors: 郭晓军
Original assignee: Shenzhen Rts Cleaning Technology Co ltd
Current assignee: Shenzhen Rts Cleaning Technology Co ltd
Priority date: 2017-06-13
Filing date: 2017-06-13
Publication date: 2022-01-18
Anticipated expiration: 2037-06-13
Also published as: CN107354460A

Abstract

The invention relates to a surface treatment liquid for integrally molding stainless steel and plastic, which consists of an etchant, an auxiliary etchant, a complexing agent, a solvent and a surfactant, wherein the etchant accounts for 20-50 parts by mass, the etching aid accounts for 3-20 parts by mass, the complexing agent accounts for 1-10 parts by mass, the solvent accounts for 5-20 parts by mass and the surfactant accounts for 0.5-3 parts by mass based on 100 parts by mass of the total amount of a chemical etching liquid. The optical film disclosed by the invention has the characteristics of high resolution, high display quality, high resistance to ambient light and soft feeling for people to watch. By the surface treatment of the surface treatment liquid, uniform holes are formed on the surface of the metal matrix, and the size of the stainless steel matrix is not influenced. The depth of the holes is controllable, the hole is suitable for being removed in subsequent procedures of mechanical CNC, grinding, polishing and the like, and the decoration of the appearance surface is facilitated.

Description

Surface treatment liquid for integrated forming of stainless steel and plastic

Technical Field

The invention relates to a stainless steel surface treatment method, which is suitable for a stainless steel-plastic integrated molding technology, in particular to a machine frame stainless steel and high-strength organic synthetic resin linked complex in the field of 3C electronics.

Background

From the trend of consumer electronics, 3C appearance innovation has gone from plastic to metal chassis, because metal behaves completely differently from plastic in terms of performance and feel. In recent years, aluminum alloy metal casings are developed rapidly, and the aluminum alloy metal casings are widely applied to the field of 3C shells due to good processing performance, light weight and rich anode appearance colors. However, the anodic oxide film layer has insufficient hardness, wear resistance and weather resistance, and the dye layer on the surface is easy to fall off along with daily use friction and slightly collides to cause appearance defects.

From the material perspective, the metal enclosure provides a certain degree of shielding for radio signals; the metal closed loop structure of the mobile terminal has an obvious electromagnetic shielding effect, the mobile phone cannot normally receive signals, and the engineering plastics have no interference and shielding effect on wireless signals, so that the engineering plastics are a good choice for connecting between metals.

Consumers have made new demands on the beauty and texture of electronic products. The stainless steel has high strength, the metal surface after film coating has high hardness and multicolor appearance, and the stainless steel metal outer frame is expected to become a new breakthrough after aluminum alloy.

At present, the combination method of stainless steel and organic synthetic resin mainly comprises 2 methods, one is to combine the stainless steel and the resin together by using an organic adhesive; and the other method is to etch holes with specific shapes on the surface of the stainless steel through chemical and electrochemical corrosion, so as to combine the metal and the resin. However, the adhesive has limited bonding strength, and subsequent processing procedures are not acid and alkali resistant, and are not suitable for seamless combination of stainless steel and plastic.

The major praise corporation of japan proposed a NMT treatment process for high-strength engineering resin, Mg, Al, and stainless steel without using an adhesive, and applied to a process for integrally molding polyphenylene sulfide (PPS) and polybutylene terephthalate (PBT).

U.S. Pat. No. 8784981 describes a process for integrally molding stainless steel and plastic PBT, PPS, the anodic process can be carried out in an electrolyte of 1% -10% nitric acid, 10g/L-100g/L ferric chloride and about 1g/L-10g/L thiourea additive or about 4g/L-40g/L sodium potassium tartrate, the current density is 1A/dm2-10A/dm2, and the average pore diameter of a porous membrane on the surface of the stainless steel is 100nm-500 nm.

Chinese patent CN105500600A discloses a stainless steel surface treatment process, which adopts different compositions of sulfuric acid, citric acid and phosphoric acid to carry out pretreatment, and then carries out electrochemical treatment of alkaline solution or acid solution soaking treatment. The pore size distribution is 100-.

However, the above different process technologies are suitable for injection molding with engineering plastics such as PBT, PPS and the like, but have unsatisfactory bonding force with PAEK polyaryletherketone, IXEF polyaromatic amide and the like, thereby limiting the application range.

Disclosure of Invention

Aiming at the defects in the prior art, the novel technology for stainless steel metal surface treatment is researched, the novel technology is suitable for more high-molecular synthetic resins, and the stainless steel-plastic integrated manufacturing method is realized through the following technical scheme.

The surface treatment liquid for the integrated molding of stainless steel and plastic comprises an etchant, an auxiliary etchant, a complexing agent, a solvent and a surfactant, wherein 20-50 parts by mass of the etchant, 3-20 parts by mass of an etching aid, 1-10 parts by mass of the complexing agent, 5-20 parts by mass of the solvent and 0.5-3 parts by mass of the surfactant are matched with 100 parts by mass of the total amount of the chemical etching liquid.

Furthermore, the etching agent consists of 5 to 50 percent of ferric chloride and 5 to 20 percent of copper sulfate or copper chloride. Wherein, the etchant is preferably composed of 15% -30% of ferric chloride, 10% -20% of copper sulfate or copper chloride.

Furthermore, the auxiliary etching agent is composed of two or more than two mixed acids of hydrochloric acid, sulfuric acid and phosphoric acid, wherein the mixed acid liquid is based on the total mass, the content of the hydrochloric acid is 3-65%, the content of the sulfuric acid is 1-15%, and the content of the phosphoric acid is 0-20%.

Further, the complexing agent is composed of one or a mixture of more than two of sodium gluconate, EDTA-4Na and citric acid, wherein the total mass of the complexing agent is taken as a reference, the content of the sodium gluconate is 1-80%, the content of the EDTA-4Na is 1-15%, and the content of the sodium citrate is 1-20%.

Further, the solvent is glycerol, and the content of the glycerol is 5-20%. Among them, the content of glycerin is preferably 10 to 20%.

Furthermore, the surfactant is composed of a nonionic surfactant and an anionic surfactant, and the content of the surfactant is 0.1-5%.

The object to be treated suitable for the surface treatment liquid is stainless steel, and includes: chromium-containing stainless steel of type SUS405, SUS 429 or SUS 403; chromium-nickel stainless steel, model SUS301, SUS304, SUS316, SUS 305.

After the stainless steel is chemically treated by the surface treatment liquid, the surface of the stainless steel contains corrosion holes, the hole diameter distribution is 10-200 mu m, and the depth is 10-100 mu m.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for treating a stainless steel surface, which provides a metal resin integral molding process with excellent bonding force, simple and easy production, stable and controllable process, and low cost, based on the size of the stainless steel.

The chemical treating liquid consists of certain amount of iron ion, copper ion, inorganic acid, complexing agent, solvent and surfactant.

According to the invention, uniform holes can be formed on the surface of the metal substrate by only soaking the stainless steel in the treatment solution, and the size of the stainless steel substrate is not influenced. The depth of the holes is controllable, the hole is suitable for being removed in subsequent procedures of mechanical CNC, grinding, polishing and the like, and the decoration of the appearance surface is facilitated.

The chemical treatment liquid preferably contains at least iron ions, copper ions, chloride ions, and hydrogen ions. The stainless steel is formed with excellent hole appearance by chemical etching, and can effectively prevent the stainless steel from general corrosion. Secondly, for 100 parts by mass of the total amount of the chemical treatment liquid, a mixed acid system of 15-30% of ferric chloride, 10-20% of copper sulfate or cupric chloride and 5-20% is preferred.

In addition, the treatment solution containing the complexing agent can improve the solubility of metal ions in the treatment solution, effectively control the effective contents of iron ions and copper ions in the bath solution, release the iron ions and the copper ions as required, and simultaneously, the complexing of corroded metal ions such as nickel and chromium is effective, thereby providing a stable chemical treatment solution. The content of the complexing agent is preferably 1 to 20% with respect to 100 parts by mass of the total amount of the chemical treatment liquid.

And the treatment solution containing the solvent and the surfactant can effectively reduce the surface tension of the system and effectively control the pore density of the surface of the stainless steel substrate.

The invention provides a surface treatment fluid for stainless steel-plastic integrated molding, which comprises the following substances in mass concentration: 20-50 parts by mass of an etching agent, 3-20 parts by mass of an etching aid, 5-20 parts by mass of a solvent and 0.5-3 parts by mass of a surfactant are mixed.

Detailed Description

The technical solutions in the summary of the invention will be clearly and completely described below with reference to the embodiments of the invention, and it is obvious that the described embodiments are only a part of the embodiments of the invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In order to make the technical problems solved by the present invention more clear, the present invention will be further described in detail with reference to the following embodiments, which are described herein for the purpose of illustration only and are not intended to limit the present invention.

The invention is characterized in that the shape of the etching hole can be effectively controlled in the stainless steel etching process, and the size of the stainless steel is not influenced.

The surface treatment liquid for the stainless steel-plastic integrated molding provided by the invention has excellent surface corrosion performance, and the treatment liquid tank can be continuously used for a long time and can be replenished according to needs. The preparation comprises the following substances in mass concentration: 20-50 parts by mass of an etching agent, 3-20 parts by mass of an etching aid, 5-20 parts by mass of a solvent and 0.5-3 parts by mass of a surfactant are mixed. If the concentration of the etchant is higher than 50%, the risk of insoluble precipitation is generated, and the etchant cannot play an etching role below 20 g/L; the concentration of the etching auxiliary agent is lower than 3g/L, the etching speed is too slow and higher than 20g/L, and the bath solution correspondingly accumulates too many side response products to influence the service life of the bath solution; the complexing agent is preferably 1-20%, iron and copper ions are released as required in a tank liquid system, and simultaneously, the complexing agent is effective in complexing corroded metal ions such as nickel and chromium, so that the hidden danger of overall corrosion caused by stable chemical treatment liquid is provided, the treatment liquid of a solvent and a surfactant can effectively reduce the surface tension of the system, and the control of the pore density of the surface of the stainless steel substrate is effective.

Degreasing the stainless steel, wherein the degreasing process comprises the step of immersing the degreasing agent for about 5-15 minutes, and the degreasing process is combined with RTS305B which is a product of Honxinda corporation, so that the ultrasonic effect is better, and air can be bubbled if the ultrasonic effect is not provided. Then rinsed well in water.

The stainless steel is activated to remove the oxide film formed on the second surface of the stainless steel. The activation process comprises soaking the stainless steel in an acidic solution, which may be a sulfuric or hydrochloric acid solution, or a mixture thereof, at room temperature for about 1-2 min. When a sulfuric acid solution is used, the mass percent of sulfuric acid in the acidic solution is about 15% to 35%. In the exemplary embodiment, the stainless steel is soaked in a sulfuric acid solution having a mass percent of about 15% for about 1min during the activation process, which effectively removes a layer of natural oxides of iron formed on the surface of the stainless steel without corroding the substrate. That is, no significant pores or grooves are formed on the stainless steel surface during activation. When the activation process is over, the stainless steel is washed thoroughly.

The present invention will be described in further detail with reference to specific examples.

The composition of the treatment liquid is as follows: 20% of ferric trichloride, 10% of copper sulfate, 10% of hydrochloric acid, 5% of complexing agent, 10% of glycerol and 0.5% of surfactant;

As shown in Table 1, for the polishing process, the treated test pieces were stainless steels of type SUS304, SUS316 and SUS316L, respectively, and the treatment process was as follows:

cleaning: soaking in RTs305B solution with concentration of 10-30% and temperature of 70-80 deg.C for 60-180 s, and bubbling;

washing with water: soaking for 60-180 seconds at room temperature by pure water, and bubbling;

and (3) activation: soaking in 15% concentration sulfuric acid solution at room temperature for 60-180 sec, and bubbling;

then the water washing process is carried out once;

etching treatment: soaking the surface treatment liquid stock solution at 60-100 ℃ for 180-600 seconds, and bubbling;

then the water washing process is carried out once;

neutralizing: soaking in RTs322 solution with concentration of 10-20% at room temperature for 60-180 s, and bubbling;

then the washing process is carried out twice;

and finally, carrying out a drying injection molding process.

Table 1:

the test results are shown in the following table 2, and after stainless steels SUS304, SUS316 and SUS316L are treated, the surface hole size is 20-100 μm, the test of tensile force >15MPa is passed, the injection molding is not sticky, and the high temperature and high humidity, thermal shock and air tightness test can be passed.

Table 2:

although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

1. The surface treatment liquid for the integral molding of stainless steel and plastic comprises an etchant, an etching assistant, a complexing agent, a solvent and a surfactant, wherein 20-50 parts by mass of the etchant, 3-20 parts by mass of the etching assistant, 1-10 parts by mass of the complexing agent, 5-20 parts by mass of the solvent and 0.5-3 parts by mass of the surfactant are matched with 100 parts by mass of the total amount of the surface treatment liquid, and the surface treatment liquid is characterized in that:

based on the total mass of the complexing agent, the content of sodium gluconate is 1-80%, the content of EDTA-4Na is 1-15%, and the content of sodium citrate is 1-20%;

the solvent is glycerol;

the surfactant is composed of a nonionic surfactant and an anionic surfactant;

chromium-containing stainless steel and chromium-nickel stainless steel are the objects of the surface treatment liquid.

2. The surface treatment liquid according to claim 1, wherein the object to be treated with the surface treatment liquid comprises: chromium-containing stainless steel of type SUS405, SUS 429 or SUS 403; chromium-nickel stainless steel, model SUS301, SUS304, SUS316, SUS 305.