JPS63149384A - Method for plating polyamide resin - Google Patents

Abstract

PURPOSE:To form a plated layer having fine appearance and superior adhesion on a molded product of polyamide resin by etching the molded product with an aq. soln. contg. 2-5C alpha-halogenated aliphatic carboxylic acid and a mineral acid and by subjecting the product to neutralization, sensitization, activation, electroless plating and electroplating. CONSTITUTION:A molded product of polyamide resin is washed by a conventional method as required and it is etched with an aq. soln. contg. 5-50g/l 2-5C alpha-halogenated aliphatic carboxylic acid such as monochloroacetic acid and 20-175g/l mineral acid such as sulfuric acid or hydrochloric acid. The etched molded product having a sufficiently roughened surface is neutralized with an aq. soln. of an alkali such as NaOH and reneutralized with a dil. aq. soln. of a mineral acid to perfectly remove the adsorbed alkali. The neutralized molded product is sensitized and activated by a well known method and the pretreated molded product is subjected to electroless plating and electroplating as usual.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a plating method for forming a plating layer with excellent appearance and adhesion on a polyamide resin molded product.

[Conventional technology]

When plating a polyamide resin molded product, (1) degreasing treatment (2) etching treatment (3) sensitivity imparting (4)
) Activation treatment (5) Electroless plating treatment (6) Electroplating treatment It is already known that a metal plating layer can be formed on the surface of a molded article.

Etching agents used in the above plating process include an aqueous solution of chromic acid and sulfuric acid (used for plating ABS resin), an aqueous solution of stannic chloride and hydrochloric acid (Japanese Patent Application Laid-open No. 57
-98530), borofluoric acid or hydrofluoric acid aqueous solution (JP-A-57-8228), hydrochloric acid aqueous solution (JP-A-57-8228),
7-100139, Japanese Patent Publication No. 57-123231), etc. are known.

However, when the above etching agent is used in polyamide resin moldings, the surface of the material is insufficiently roughened, resulting in the formation of a plating layer with low adhesion, and the material itself becoming brittle due to the etching solution penetrating into the material. It has drawbacks such as oxidation and impairing the surface smoothness of the material.

[Problem that the invention seeks to solve]

The present invention aims to improve the problems of the prior art and provide a method for forming a plated layer with good adhesion on a polyamide resin molded product to obtain a plated product with no decrease in strength and excellent appearance. With the goal.

[Means for solving problems]

As a result of intensive research, the present inventors found that as an etching agent,
The above object was achieved by using an aqueous solution containing an α-halogenated aliphatic carboxylic acid having 2 to 5 carbon atoms (first component) and a mineral acid (second component) and by the processing method described below.

The plating process in the present invention is performed by the following method.

(1) First step (cleaning, etching) First, the polyamide resin molded material, which is a raw material, is washed according to a conventional method as required, and then treated with the etching treatment liquid of the present invention.

Specifically, the cleaning operation includes immersion in an organic solvent (e.g., trichlorethylene, alcohol, etc.), immersion in an alkaline solution (e.g., sodium phosphate, sodium borate, etc.), or This is done by soaking in a commonly used neutral detergent based on higher alcohol and then washing with water.

Next, an etching process is performed, and the first component of the etching solution used in the present invention is an .alpha.-halogenated aliphatic carboxylic acid having 2 to 5 carbon atoms represented by the following two general formulas.

(i) C, H, □lCH2-, (X), C00H (ii
) C(X) 3 C0OH Explanation of abbreviations in the above formula X: Halogen element of any of F, CI, Br m: 1-
Integer neo of 2 to integer 3 Compounds included in the above formula include, for example, monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, monochloropropionic acid,
Examples include dichloropropionic acid, monochlorobutyric acid, dichlorobutyric acid, monochlorovaleric acid, dichlorovaleric acid, and fluorine- or bromine-substituted products thereof.

The above α-halogenated aliphatic carboxylic acids may be used alone or in combination of two or more.

The amount used is usually 5 to 500 g/l in the etching solution.
, preferably in an amount resulting in a concentration of 10 to 300 g/l.

The second component mineral acid used in the etching solution is hydrochloric acid or sulfuric acid. This second component can be used alone or in combination.

The amount of this second component used is usually 20 to 20% in the etching solution.
The amount gives a concentration of 175 g/l, preferably 35-105 g/l.

The above etching treatment is performed by etching the material for 10 seconds to 10 minutes at a temperature of usually 20 to 60°C, preferably 30 to 45°C.
It is preferably carried out by dipping for 15 seconds to 5 minutes.

Even by such a short-time treatment, the surface of the material is sufficiently roughened, and the material is not altered in quality or its appearance is impaired.

(2) Second step (neutralization) The etched material is immersed in an alkaline aqueous solution,
Perform neutralization treatment.

As the alkaline component of this neutralization treatment liquid, sodium hydroxide, potassium hydroxide, ammonium hydroxide, etc. can be used.

The concentration of this alkaline component is 10-50 g/l, preferably 20-30 g/l.

The neutralization treatment here is carried out at a temperature of room temperature to 45°C.
This is done by soaking for ~3 minutes. The neutralization treatment here removes acidic components excessively adsorbed on the surface of the material and improves the deposition properties of the plating in the electroless plating process in the fifth step described below.

(3) Third step (re-neutralization) The material neutralized in the second step is immersed in an aqueous mineral acid solution to perform re-neutralization.

The mineral acid used here is 7 to 7 when using 36% hydrochloric acid.
35 g/l, preferably at a concentration of 10 to 20 g/l. The re-neutralization treatment is carried out by soaking for 1 to 5 minutes at a temperature of 20 to 60°C, preferably 30 to 45°C.

By this neutralization treatment, the alkali components adsorbed in the second step are completely removed, and the sensitization in the next step is smoothly performed.

(4) Fourth step (sensitization and activation treatment) Sensitization and activation can be carried out according to known methods.

(5) Fifth step (electroless plating, electroplating) Electroless plating and electroplating can be performed by a normal method.

By performing a series of plating treatments according to the present invention, a plated layer with excellent appearance and adhesion can be formed, and an excellent plated product can be obtained in which the physical properties of the molded product are not deteriorated by the main plating treatment.

Polyamide resins that can be used in the present invention include diamines such as metaxylylene diamine, hexamethylene diamine, nonamethylene diamine, undecamethylene diamine, and dodecamethylene diamine, and terephthalic acid, isophthalic acid, adipic acid, sebacic acid, and dodecane dibase. acid,
Polymers obtained by polycondensation with dicarboxylic acids such as geltaric acid, or copolymers thereof, and other ε-caprolactam, aminocaproic acid, enantholactam, 7-aminohebbutanoic acid, 11-aminoundecanoic acid, 9- Polymers such as aminononanoic acid, 2-pyrrolidone, and 2-piperidone, and thermoplastic resins (e.g., ethylene/α-olefin copolymers, ethylene/vinyl ester copolymers, and acid-modified products) are added to the above polymers. , ABS resin, etc.).

Glass fibers, carbon fibers, and inorganic fillers (e.g., talc, mica, clay, wollastonite, calcium sulfate, calcium carbonate, aluminum oxide, silica, titanium oxide, potassium titanate single crystal fibers,
Examples include diatomaceous shells. ) can also be used as the material of the present invention. These fillers are usually blended in an amount of 5 to 70% by weight based on the polyamide resin.

[Action and effect of invention]

According to the present invention, a plating layer that is excellent in appearance, adhesion, strength, and depositability can be formed on a polyamide resin.

The products plated according to the present invention have extremely excellent performance as described above, and can of course be used as metal substitutes in the decorative field, as well as for automobiles that require mechanical properties and heat resistance. It is extremely useful in fields such as electronic equipment parts and electromagnetic shielding parts for electronic equipment.

〔Example〕

Hereinafter, the present invention will be explained in detail with reference to Examples.

In addition, all the capacities in the examples are measured values at 20° C., and “parts” in the examples indicate parts by weight.

Furthermore, performance evaluation and strength measurement of the plated molded product were performed as follows.

(Appearance of 11 plating layers Based on visual judgment. The evaluation criteria were as follows.

○: Good (surface is clean, smooth, and shiny): Slightly poor (surface is slightly rough, rough, and has some unevenness) ×: Poor (surface is uneven, not smooth, and lacks shine) (2) It shows the percentage of the area on which a plating layer was formed on a plated precipitation test piece.

(3) Adhesion strength of plated layer 1 on the plated surface of the plated polyamide resin molded plate
A cm-wide cut was made, and the force (Kg/cm) when peeling off the plating layer while pulling it in a direction perpendicular to the substrate was measured.

Measurements were performed on all the cut portions of the test piece, and the measurement results show both the maximum adhesion force and the minimum adhesion force among those measured for each cut portion.

(4) Tensile strength (retention rate) Tensile strength is measured according to ASTM D638 (measurement 't
LK: 20°C).

The measurement results are expressed as relative values of the tensile strength before and after plating, based on the tensile strength before plating.

Example 1 45 parts of poly(methaxylylene adipamide) with a number average molecular weight of 16,000, 6,610 parts of nylon, nylon 6.
5 parts, wollastonite (average particle size: 3.5 microns,
Manufactured by NYCO, USA, Wlast Cup 10M-1100)
After mixing 30 parts of potassium titanate single crystal fiber (average particle size: 0.2 microns, average fiber length: 20 microns, manufactured by Otsuka Chemical Co., Ltd., TEISMO D-102) in a mixer, the axle screw Using a mold extruder, the mixture was melt-kneaded at a cylinder temperature of 270°C and extruded into a strand, cooled in a water bath and cut into pellets.
A pellet-shaped molding material was obtained by drying.

Using this pellet-shaped molding material, a flat plate (70n+mX 70mmX 3mm) and AST were manufactured under the following injection conditions.
MD638 tensile test pieces were molded and used as test materials.

Test piece molding conditions: Mold temperature: 130°C Resin temperature: 270°C Injection time: 10 seconds Cooling time: 18 seconds The plating process was performed using a method consisting of the following five steps.

(11 First Step (Cleaning, Etching) For cleaning, the test piece was immersed in trichlorethylene for 5 minutes at room temperature, and then dried.

Next, etching was performed at 35° C. for 1 minute using an etching solution (an aqueous solution having the composition shown below).

Etching liquid composition Dichloroacetic acid 60 g/1 36% hydrochloric acid 87.5g/l After etching, it was washed with water.

(2) Second step (neutralization) Add alkaline neutralizing solution (aqueous solution with the following composition) for 3 minutes at room temperature.
l ffl and then washed with water.

Neutralization liquid composition: Caustic soda 20g/1 (3) Third step (re-neutralization) The sample was immersed in a re-neutralization liquid (an aqueous solution having the following composition) at 35°C for 3 minutes, and then washed with water.

Re-neutralization liquid composition: 36% hydrochloric acid 17.5g/1(4) 4th
Process (Improving Anger Responsiveness and Activation Treatment) Sensitization was imparted by immersing the sample in a sensitizing solution (an aqueous solution having the following composition) at 35° C. for 3 minutes.

Sensitizing liquid composition: Enilex CT 50 manufactured by Ebara 1-Syrite Co., Ltd.
m71 36% hydrochloric acid 17.5g/
1st, add 3% to the activation treatment solution (aqueous solution with the following composition) at 35°C.
Activation treatment was performed by soaking for a minute, followed by washing with water.

Activation treatment liquid composition: 36% hydrochloric acid 17.5g/] (5)
Fifth step (electroless plating and electroplating) The obtained test piece was plated using an electroless plating solution (aqueous solution with the following composition).
Electroless plating treatment was performed at H8.6 at a temperature of 35° C. for 10 minutes.

Electroless plating solution composition: Eniremax Mu-1100m/manufactured by Ebara Nishilite Co., Ltd.
1 Ebara Eichi Silite Anyrefx MU-210
After washing with water at 0 m/1, PDC treatment agent (concentration: 20 m171) manufactured by Ebara Nishilite Co., Ltd. and 95% sulfuric acid (concentration: 230 m2) were added.
ml/1) for 1 minute at room temperature.

Next, electroplating was performed using an electroplating solution (bright copper sulfate plating aqueous solution having the following composition) at a current density of 4 A/dm2 at room temperature for 60 minutes.

Electroplating liquid composition: Copper sulfate 200g/195% sulfuric acid 40g/1 UBACmon U manufactured by Ebara Nishilight Co., Ltd. 4ml/1 UBACEP manufactured by Ebara Nishilight Co., Ltd. 0. 3ml/136% hydrochloric acid
After 0.1ml/1 electroplating treatment,
It was washed with water, then air-dried at 100° C. for 1 hour, and after being left for 1 day, the adhesion strength of the resulting skin layer and the tensile strength of the tensile test piece were measured.

Furthermore, in order to determine the appearance of the plated test pieces, electroplating was performed using a bright nickel plating solution and then a chrome plating solution having the following compositions, and the appearance of the plated products was observed.

The plating conditions are also described below.

(i) Bright nickel plating solution Bright nickel plating solution composition (aqueous solution): Nickel sulfate
300 g/nickel monochloride
70g/l boric acid 40g/
11- Brightener #610 manufactured by Silite Co., Ltd. 10m 1/1 Silite Co.'? AN H'lA agent #6 2
5ml/1 Sillite Brightener #63
15m1/1 nickel plating processing conditions: Bath temperature 60℃ Current density 4A/dm2 Time 15 minutes (11) Chrome plating conditions Chrome plating solution composition (aqueous solution) Dichromic acid 240g/195% sulfuric acid
1 g/l Microlite KC-404g/1 made by Ebara Sucilite Co., Ltd. 1 Zero Mist HT-20, made by Ebara Eichilight Co., Ltd. 5 g/1 Chromium plating processing conditions: Bath temperature 50℃ Current density 19A/dm" Time 2 minutes Evaluation results are shown below. It is shown in Table 1.

Example 2 Using the same material as used in Example 1, it was immersed in trichlorethylene for 5 minutes at room temperature and washed, and then dried.

Next, this test piece was treated with a notching solution having the following composition.
Etching treatment was performed at 5°C for 3 minutes.

Etching solution composition (aqueous solution) Trichloroacetic acid 20 g/1 36% hydrochloric acid 87.5g/l Thereafter, the same processing and treatments as in Example 1 were performed.

The evaluation results are shown in Table 1.

Comparative Example 1 This comparative example was based on a conventional etching treatment method, and the following treatments were performed.

A test piece of the same material as used in Example 1 was previously cleaned using trichlorethylene (under the same conditions as Example 1), etched using the comparative etching solution shown below at 40°C for 110 minutes, and then washed with water.

Comparative etching solution composition (aqueous solution): 36% hydrochloric acid 100 g/l Thereafter, the alkali neutralization treatment (second step) and re-neutralization treatment (third step) in Example 1 were omitted, and the treatments after sensitization were performed. was the same as in Example 1.

The evaluation results are shown in Table 1.

Comparative Example 2 A test piece of the same material used in Example 1 was cleaned in advance using trichlorethylene (under the same conditions as Example 1), etched with the comparative etching solution shown below at 40°C for 20 minutes, and then washed with water. did.

Comparative etching solution composition (aqueous solution): Second m chloride 300ml/1 36% hydrochloric acid 20 g/1 Thereafter, the same treatment as in Example 1 was performed.

The evaluation results are shown in Table 1.

Comparative Example 3 Using the same material as in Example 1, the same mebuki processing as in Example 1 was performed, except that only the alkali neutralization treatment (second step) was omitted.

The evaluation results are shown in Table 1.

Chapter 1 Table

Claims (1)

[Claims] When plating a polyamide resin molded product, after cleaning the material according to a conventional method as necessary, an α-halogenated aliphatic carboxylic acid having 2 to 5 carbon atoms (first component) and a mineral acid ( Etching is performed using an aqueous solution containing (second component) (first step), neutralized with an alkaline aqueous solution (second step), and re-neutralized with a dilute aqueous solution of mineral acid (third step).
step), sensitization and activation treatment (fourth step), then electroless plating and electroplating (fifth step),
A method for plating polyamide resin characterized by