JPH0210226B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an etching method and an etching agent for polyamide resin molded articles, and more specifically, the present invention relates to a method for etching polyamide resin molded articles and an etching agent.
A method for etching a polyamide resin molded article, which comprises immersing the polyamide resin molded article in an aqueous solution containing a metal halide belonging to group a, a, a, or Ib, and a reducing agent, and the etching agent. It is.

Usually, the methods for plating plastic molded products include applying a conductive substance to the surface and then applying electroplating, and a process called etching depending on the properties of each plastic. After that, plating is chemically deposited on the surface,
It is further divided into two methods: electroplating.
The present invention belongs to the latter method and relates to improvements in the etching step therein.

This etching process is an extremely important process that not only determines the adhesion between the base plastic and the plating film, but also greatly influences the appearance of the plated product.

Although the mechanism of action of etching on plastic molded products has not yet been completely elucidated, it is generally explained as follows.

The surface layer of a plastic molded product is chemically attacked by the etching agent during the etching process, creating fine pores and unevenness, which serve as footholds for the plated metal film that precipitates in the subsequent process (usually referred to as the Ikari effect). . Incidentally, the surface of these eroded portions simultaneously generates hydrophilic polar groups, which facilitate the deposition of plating and at the same time promote adhesion. Therefore, if the degree of erosion is small, the surface of the molded product will remain in a state close to that at the time of molding, and as a result, a plating with a good appearance will usually be obtained. Since there are few or shallow layers, the adhesion of plating is weak. Furthermore, if the degree of erosion is excessive, the surface of the molded product will become extremely rough, and the surface of the resulting plating film will also be rough and have a poor appearance. Furthermore, if the erosion becomes excessive, the foothold effect will be reduced and the adhesion will also be reduced. Furthermore, it is said that if the state of the resulting hydrophilic polar groups is not appropriate, the deposition of the plating metal tends to be non-uniform and the adhesion is also reduced.

Although the effects of etching are very complex, etching is an important processing step that determines the quality of the final plated product.

Conventionally, most of the base materials used for plastic plating are ABS resin,
Due to its characteristics, its use was limited to decorative purposes.

For this reason, in recent years, attention has been focused on plating polyamide resins that have better mechanical properties, heat resistance, weather resistance, and other functional properties, and several plating methods have been proposed. Until now, the treatment chemicals for the etching process, which is the key point, have been
(1) Chromic acid aqueous solution, (2) chromic acid and sulfuric acid aqueous solution, (3) borofluoric acid aqueous solution, (4) iodine and potassium iodide aqueous solution, (5) hydrochloric acid or sulfuric acid aqueous solution, (6 ) Aqueous solutions of hydrochloric acid and sulfuric acid are used.

However, all of these etching agents have problems in the above-mentioned balance between adhesion and appearance, and it is difficult to say that they are necessarily satisfactory in practice.

Further, JP-A-57-98529, JP-A No. 57-98530, and JP-A No. 56-129232 disclose aqueous solutions of chlorides of elements of groups or groups of the periodic table, aqueous solutions of mixtures of tin chloride and acids, Alternatively, an etching solution comprising an aqueous solution of stannic chloride is disclosed. However, these etching solutions had a serious drawback in that the etching activity decreased in a short period of time.

The object of the present invention is to provide an etching method that eliminates the drawbacks of the conventional methods and provides an excellent appearance and good adhesion.

It is also an object of the present invention to provide an etching agent for use in the above etching method.

As a result of intensive research to achieve the above object, the present inventors discovered that hydrochloric acid or sulfuric acid, a halide of a metal belonging to group a, a, a, a, or Ib of the periodic table of elements, and a reducing agent. The present inventors have discovered that an aqueous solution containing the above is extremely excellent as an etching solution for polyamide resin molded articles, and have completed the present invention.

Therefore, a preferred embodiment of the present invention is to combine hydrochloric acid or sulfuric acid with a, a, a, a,
, or an etching agent for polyamide resin molded articles comprising an aqueous solution containing a metal halide belonging to group Ib and a reducing agent, and an etching agent for polyamide resin molded articles characterized by immersing the polyamide resin molded article in the etching agent. This is an etching method.

Typical examples of the metals used in the present invention include titanium, vanadium, chromium, manganese,
Examples include iron, cobalt, nickel, copper, palladium, platinum, and gold. These metal halides include chloride, fluoride, bromide,
Although any iodide can be used, it is generally preferred to use chloride because it is readily available.

The amount of halide used as the metal salt is:
Although the lower limit is 0.5 g/m and it is possible up to the saturated dissolution amount of each compound, it is preferable to decide in consideration of the balance with the acid used, workability, and economical production.

The etching agent of the present invention may contain various stabilizers for increasing liquid stability and various surfactants for decreasing surface tension and increasing processing effects.

The etching agent of the present invention must contain hydrochloric acid or sulfuric acid. The amount of acid used is selected so that etching of the polyamide resin molded article is appropriately promoted. Generally, when using hydrochloric acid, the concentration is usually 400 ml or less, preferably 350 ml or less as 35% hydrochloric acid. Further, when using sulfuric acid, the concentration is preferably 200 ml or less as 98% sulfuric acid. If the concentration of the acid used is higher than the above range, the etched surface will dissolve, leading to excessive etching and significantly deteriorating the appearance or adhesion of the plating, which is not preferable.

It is necessary to add a reducing agent such as sodium hypophosphite, formalin, hydrazine, or sodium bisulfite to the etching solution of the present invention. By adding such a reducing agent, the stability of the etching solution is improved and it becomes possible to use it for a long time. The amount of reducing agent to be added may be any amount effective for improving stability, and generally about 0.5 to 20 g/g is appropriate.

The etching temperature can range from 25 to 65°C depending on the processing time and etching effect, but is preferably in the range of 40 to 60°C.

The etching time is not particularly limited, but is generally 1 to 30 minutes, preferably 5 to 25 minutes.

The mechanism of action of the etching agent of the present invention has not been fully elucidated at present. However, the degree of corrosion on the surface of the polyamide resin molded product etched with this etching agent is lower than that of conventional products, and even after sufficient water washing after treatment, the surface of the polyamide resin molded product etched with the etching agent is free of the metal used or its ions. Considering that their presence is observed, there is a strong possibility that these "metal ions" are involved in the structure and physical properties of hydrophilic polar groups on the eroded surface, and as a result, despite the small degree of erosion roughening. It is thought that good adhesion of the plating film can be obtained.

In addition, this etching agent has good workability because it does not contain chromic acid like the conventional etching bath, and the waste liquid and its washing water, including the liquid during use, do not contain chromic acid.
It can be used in wastewater treatment, etc., without the need for particularly complicated post-treatment.

As the polyamide molded article in the present invention, any plating grade polyamide molded article can be used. Blends with other thermoplastics,
Alternatively, polyamide molded products containing an inorganic filler are also included in the polyamide molded products usable in the present invention.

Next, the present invention will be explained in more detail with reference to Examples. Polyamide (nylon 6) molded product (plate shape,
1 dm ² , 5 sheets each) were pretreated and plated using a conventional method. That is, this molded product is treated with a degreasing agent (Kizai Co., Ltd.).
After degreasing by immersing the sample in 30g/aqueous solution of MacScreen NG-30 (manufactured by Manufacturer Co., Ltd.) at 50°C for 5 minutes, it was washed with water. Next, this was subjected to immersion etching treatment using each bath composition and conditions shown in the examples below, and then washed with water.
Add this to 10 g of stannous chloride and concentrated hydrochloric acid per 1 water.
After sensitizing the sample by immersing it in a solution containing 15 ml of the sample at 20°C for 2 minutes, it was washed with water. Next, it was activated by immersing it in a solution of 0.1 g of palladium chloride and 10 ml of concentrated hydrochloric acid per water at 30° C. for 1 minute, and then washing with water. Next, it was immersed in a chemical copper plating solution (manufactured by Kizai Co., Ltd., Cp-Cu solution) at 25° C. for 10 minutes to perform chemical copper plating, and then washed with water. Furthermore, water 1
200g of copper sulfate, 50g of concentrated sulfuric acid and 5ml of brightener
2.5A/dm 2 , current density 2.5A/dm ² ,
After bright copper plating at 25°C for 60 minutes, it was washed with water. After leaving the obtained product for 24 hours at room temperature,
The adhesion strength of the plated metal film and its appearance (presence or absence of gloss, presence or absence of abnormalities such as cracks, pits, and roughness) were investigated.

In addition, for the adhesion test, a rectangular cut of 1 cm x 10 cm was made on the plating film of the obtained test piece.
The end piece of the plating film was pulled and the peel strength at that time was measured. In addition, the quality of appearance was determined visually.

Example 1 Hydrochloric acid 50ml/ Ferrous chloride 250ml/ Sodium hypophosphite 4ml/ Water Remainder Temperature 55℃ Time 10 minutes Results: Peel strength, average 1.6Kg/cm Appearance, good gloss, no other abnormalities, Implementation Example 2 Sulfuric acid 150ml/ Cuprous chloride 300g/ Formalin (37%) 20ml/ Water Remainder Temperature 40℃ Time 20 minutes Results: Peel strength, average 1.5Kg/cm Appearance, good gloss, no abnormalities, Example 3 Hydrochloric acid 150ml/ Manganese chloride () 25g/ Hydrazine 5ml/ Water Remainder Temperature 50℃ Time 20 minutes Results: Peel strength, average 2.0Kg/cm Appearance, good gloss, no abnormalities Example 4 Hydrochloric acid 200ml/ Vanadium chloride () 5g/ Sodium bisulfite 2g/ Water Remainder Temperature 60℃ Time 8 minutes Results: Peel strength, average 2.0Kg/cm Appearance, good gloss, no abnormalities, Example 5 Sulfuric acid 200ml/ Cobalt chloride () 50g/ Sodium hypophosphite 20g/ Water balance Temperature 45℃ Time 12 minutes Results: Peel strength, average 1.4Kg/cm Appearance, good gloss, no abnormalities, Example 6 Hydrochloric acid 300ml/ Palladium chloride () 0.5g/Next Sodium phosphite 0.5g/ Water balance Temperature 55℃ Time 15 minutes Results: Peel strength, average 1.8Kg/cm Appearance, good gloss, no abnormalities, Example 7 Hydrochloric acid 350ml/ Platinum chloride () 1g/ Formalin 1ml / Water balance Temperature 55℃ Time 10 minutes Results: Peel strength, average 1.5Kg/cm Appearance, good gloss, no abnormalities, Example 8 Hydrochloric acid 300ml/Chromium chloride () 5g/Hydrazine 0.5g/Water balance Temperature 50℃ Time: 12 minutes Results: Peel strength, average 2.0 Kg/cm Appearance, good gloss, no abnormalities As can be seen from the results of the examples, the molded products obtained by plating the etched polyamide resin molded products according to the present invention The peel strength of the glitter coatings was higher than the practically required value of 0.8 kg/cm, and their appearance was good, with good gloss and no other abnormalities were observed on the surface.

Claims (1)

[Claims] 1 Hydrochloric acid or sulfuric acid and a, a, on the periodic table
1. A method for etching a polyamide resin molded article, which comprises immersing the polyamide resin molded article in an aqueous solution containing a metal halide belonging to Group A, A, or Ib group and a reducing agent.