JPH06279609A - Synthetic resin molded product - Google Patents

Abstract

PURPOSE:To provide the subject inexpensive molded product having an electroless plated intermediate layer and an electrolytic aluminum-plated layer on a synthetic resin substrate and useful for electric appliances, automotive part items, etc., by applying a highly adhesive aluminum-plating treatment onto the surface of the substrate. CONSTITUTION:A synthetic resin substrate for an ABS front panel molded product, etc., is immersed and etched in an aqueous solution comprising chromic anhydride- sulfuric acid at 70 deg.C, washed, immersed in a solution comprising palladium chloride, stannous chloride, hydrochloric acid and water at 60 deg.C for the addition of the catalyst to produce the preliminarily treated molded product. The molded product is immersed in an aqueous solution comprising a cupric sulfate, Rochelle salt, sodium hydroxide and formalin and subjected to an electroless copper-plating treatment. The treated molded product and a steel plate as an cathode and as its counter electrode, respectively, are subjected to an electrolysis to form a copper coating film. The plated molded product and an aluminum plate as a cathode and as its counter electrode, respectively, are again subjected to an electrolysis to form an aluminum coating film thereon, thus providing the synthetic resin molded product having the electroless plated intermediate layer and an electrically plated aluminum layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synthetic resin component having an aluminum appearance, and more particularly to a synthetic resin molded product having a surface aluminized, which is used for home electric appliances and automobile parts. is there.

[0002]

2. Description of the Related Art Conventionally, parts such as automobiles and home electric appliances have been changed from metal to synthetic resin in response to demands for cost reduction and weight reduction. With regard to home electric appliance parts, the transition to synthetic resin, which is a material with good workability in response to the demand for cost reduction, the surface of synthetic resin is less luxurious than that of metal parts and is suitable for consumers' hobbies. Because it may not
Generally, black coating, metallic coating, chrome plating or the like is performed. On the other hand, aluminum is known as a metal that has beauty and a high-grade appearance, and in addition to conventional ones having appearances such as chromium and nickel, there is an increasing demand for synthetic resin parts having aluminum appearance.

Metallic coating, vacuum deposition and the like are known as methods for obtaining the aluminum appearance. However, the aluminum appearance obtained by these methods does not give a natural feeling after processing a metal. It is hard to say that it has a beautiful and luxurious appearance. Further, the vacuum deposition method has a drawback that the product cost is high.

Further, for automobile parts, the use of synthetic resin has been increasing due to the demand for weight reduction, but since it is inevitable to use together with metal parts having excellent strength, the surface of the resin is coated by a method such as plating or sputtering. It has been modified to give it a metallic appearance. For the same purpose, metallic coating is also used, which is easy to operate and low in product cost. Furthermore, a method has also been developed in which a base coat layer is provided on the surface of a resin and a metal is directly sprayed (for example, JP-A-63-56442).

On the other hand, as a method for forming an aluminum thin film having good weather resistance and adhesiveness, there are a plating method using a molten salt bath, an electroplating method using a plating solution maintained at a relatively low temperature of 200 ° C. or less, and the like. Being developed. Among them, the method using room temperature molten salt using onium salt is 1
Plating at a temperature of 00 ° C. or lower is possible (for example, JP-A-63-26399). However, this method cannot be applied to synthetic resin parts because the object to be plated has no electrical conductivity.

[0006]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems and is suitable for home electric appliances and synthetic resin molded articles for automobiles, which is difficult to form by the conventional method, and has weather resistance on the surface. It is an object of the present invention to provide a synthetic resin molded product which has been subjected to an aluminizing treatment with good adhesion at low cost.

[0007]

That is, the present invention provides a synthetic resin molded article comprising a synthetic resin substrate, an electroless plating intermediate layer, and an electroplated aluminum layer.

Examples of the synthetic resin molded article of the present invention include operation parts for home electric appliances such as switches and dials,
Examples include outer panel parts such as front panels. Also,
Examples of molded articles for automobiles include tire-related parts such as wheel caps and center caps, outer plate-related parts such as fenders and front grills, and engine-related parts such as cylinder head covers.

The size of the synthetic resin molded product is applicable to any size, but in terms of equipment and productivity, 1 m × 1.
It is desirable that the size is less than or equal to the size of an m plate, 1 m × 0.5 m × 0.5 m block.

The synthetic resin constituting the molded article includes polyolefins such as polyethylene and polypropylene, polyesters such as polystyrene, polyacrylonitrile, polyethylene terephthalate and polybutylene terephthalate, polyamides such as nylon, polycarbonate,
Examples thereof include synthetic resins such as polyethers such as polyacetal and polypolyphenylene oxide.

The electroless plating intermediate layer is formed by applying electroless plating to the above-mentioned synthetic resin molded article to provide a metal film. The electroless plating intermediate layer is silver,
Copper, nickel, gold or the like can be applied, but among these, an intermediate layer using copper plating or nickel plating is preferable in terms of processing cost. The thickness of the intermediate layer is 0.3 μm
The above is sufficient, but preferably 0.3 to 20 μ
The range is m.

The electroless plating method can be easily carried out by subjecting the surface of the synthetic resin molded article to pretreatment and then immersing it in a metal salt solution containing a reducing agent. As a pre-treatment,
Usually, the surface of a synthetic resin molded product is etched with a chromic acid-based etching solution, and a catalyst using a palladium chloride solution is applied.

A typical etching condition is to immerse the synthetic resin molded article in an aqueous solution of chromic anhydride (400 g / L) -sulfuric acid (20 vol%) at 70 ° C. for 10 to 30 minutes. If the immersion time is too short or the immersion temperature is too low, the etching does not proceed so much and the adhesion of the electroless plating intermediate layer is deteriorated, which is not preferable.
If the immersion time is too long, the smoothness of the surface will be lost.

For the immersion temperature, it is necessary to change the processing temperature in consideration of the type of synthetic resin molded product used, the maximum operating temperature and the like. For example, nylon with low heat resistance is
It seems that the minute processing is good. After etching, dilute sulfuric acid (1
0 vol%), and then dip hydrochloric acid (20 vol%) at room temperature for about 2 minutes to wash, and then wash with water.

The catalyst application using a palladium chloride solution is as follows.
For example, palladium chloride (0.5g), stannous chloride (25g), hydrochloric acid (300m)
L), a solution consisting of water (600 mL), 40 to 60
Dip for 10 minutes at ℃. Similarly, the processing temperature needs to be controlled according to the type of synthetic resin molded product used.
After applying the catalyst, it is immersed in dilute sulfuric acid (10 vol%) for washing, and then washed with water. At this time, the conditions may be room temperature and 2 minutes.

The synthetic resin molded product whose surface has been pretreated as described above is then subjected to electroless plating. The electroless plating process is performed on a metal to be plated, for example,
It is carried out by immersing the synthetic resin molded product in an aqueous solution of a metal salt containing a reducing agent such as silver, copper, nickel and gold.

As the metal salt aqueous solution containing a reducing agent, for example, in the case of copper plating, copper sulfate (7 g / L), Rossell salt (20 g / L), sodium hydroxide (5 g / L), sodium carbonate (2 g / L). L), formalin (25 mL / L)
In the case of nickel plating, the aqueous solution consisting of nickel sulfate (20 g / L), sodium hypophosphite (10 g / L)
L), lactic acid (3 g / L), sodium citrate (5 g /
L), an aqueous solution of sodium acetate (5 g / L), and the like.

The electroless plating treatment time varies depending on the required plating thickness, but is generally 5 to 60 minutes,
A plating thickness of about 0.3 μm is sufficient to provide adhesion, and thus the treatment time may be about 10 minutes. The plating temperature is generally 10 to 70 ° C.

The synthetic resin molded article of the present invention has an aluminum film on the outer surface of the electroless plating intermediate layer on the synthetic resin substrate. The thickness of the aluminum layer depends on the required appearance, but is preferably in the range of 2 to 20 μm. Generally, when a glossy appearance is required, the film thickness is 10 μm
The following is 10 μm if a die-cast-like appearance is required
The above seems to be good.

The synthetic resin molded product of the present invention may have an aluminum electroplating layer directly on the electroless plating film, but for the purpose of further improving the adhesion, or in the case of a housing of electronic parts, etc. For the purpose of simultaneously imparting electromagnetic wave shielding properties, other metals, for example, copper, nickel, chromium, zinc, tin, lead, gold, silver, rhodium, solder, etc. are electroplated and laminated and then aluminum. It is also effective to use a multi-layer that is electroplated.

For example, the conditions of acidic copper plating when performing acidic copper electroplating are copper sulfate (220 g / L),
An aqueous solution of sulfuric acid (60 g / L) was used at room temperature and a current density of 0.
It is desirable to carry out electroplating at 5-8 A / dm @ 2. The thickness of the film can be arbitrarily set depending on the electrolysis time, but 5 μm is usually sufficient. When it is desired to simultaneously provide electromagnetic wave shielding properties, it is preferable to provide a film having a thickness of about 20 μm.

The aluminum film is formed on the surface of the electroless plating intermediate layer or on the surface of the synthetic resin molded article on which the electroplating layer of another metal is formed on the electroless plating intermediate layer.
It is made by aluminum plating. At this time, the base metal is preferably copper or nickel. When the outermost layer on which aluminum electroplating is performed is made of another metal, the adhesion of the aluminum film is reduced, which is not preferable.

The aluminum electroplating method is preferably a method in which a molded product is dried and then used as a cathode, an aluminum anode (purity 99% or more) or an insoluble anode is used as a counter electrode, and a room temperature molten salt is used as a plating solution. As the room temperature molten salt, an imidazolium halide such as 1-ethyl-3-methylimidazolium chloride or a pyridinium halide such as 1-pyridinium chloride or an onium halide such as an ammonium halide such as triethylmethylammonium bromide is used alone or mixed. It is desirable to use a material (33 to 50 mol%) and an aluminum halide (50 to 67 mol%) such as aluminum trichloride or aluminum tribromide.

The aluminum plating conditions differ depending on the kind of molten salt used, but are usually room temperature to 120 ° C., current density 0.01 to 40 A / dm ² , and especially 1-ethyl-3.
It is desirable to carry out the reaction at room temperature to 60 ° C. using a room temperature molten salt composed of methyl imidazolium chloride (33 mol%) and aluminum trichloride (67 mol%).

The plating temperature needs to be changed according to the heat resistance of the synthetic resin molded product, and the usable current density range is limited depending on the temperature. Specifically, polyethylene,
Since the maximum operating temperature of nylon 6 and the like is 70 ° C, the plating temperature is preferably 50 ° C or lower. In this case, the current density range is set to 1 because the limiting current density decreases as the temperature decreases.
It is necessary to set it to 0 A / dm ² or less.

When a glossy appearance is required, it is effective to add the additive to the plating bath. An unsaturated heterocyclic compound having two or more nitrogen atoms in the ring such as pyrimidine and phenanthroline seems to be a good additive for obtaining good gloss. Further, it is desirable that the aluminum plating using the normal temperature molten salt is performed in a dry inert gas atmosphere. This is because the room temperature molten salt is unstable with respect to oxygen and moisture.

The synthetic resin molded article of the present invention has an aluminum film on the outer surface. The outer surface aluminum film thus obtained is subjected to a chromate treatment, for example, a colored treatment, for the purpose of imparting corrosion resistance. Chromate treatment can also be applied. The conditions for colored chromate include, for example, sodium dichromate (10 g / L) and sulfuric acid (0.
5 ml / L), nitric acid (3 ml / L), acetic acid (2 ml / L)
It is desirable to immerse the synthetic resin molded article of the present invention for 5 to 30 seconds in the treatment liquid consisting of L) at a temperature of 30 to 40 ° C.

[0028]

EXAMPLES Hereinafter, the present invention will be described more specifically by showing examples. The adhesion strength and thermal test in the examples were carried out by the following methods.

Tape Test: Using a safety razor single-edged blade,
Two parallel lines with a length of 50 mm at intervals of 25 mm were drawn so that the blade edge reached the surface of the synthetic resin, and an adhesive tape having a width of 25 mm and a length of 130 mm was left at 30 mm so as to cross the parallel lines at a right angle. Sticking, rubber roller (2k
g) is moved back and forth twice to be crimped. One end of the tape was pulled and the appearance after peeling off was evaluated.

Thermal test: 90 ° C per cycle
(4 hours), room temperature (0.5 hours), -40 ° C (1.5 hours), room temperature (0.5 hours), 70 ° C / 95% humidity (3 hours), room temperature (0.5 hours), -40 ° C (1.5 hours),
The appearance after two cycles of the process consisting of room temperature (0.5 hours) was evaluated. Adhesion strength: After making a notch on the surface, the edge was measured at a peeling angle of 90 ° and a peeling speed of 50 mm / min using a tensile tester.

Example 1 ABS front panel molded product (420 × 100 mm)
Chromic anhydride (400 g / L) -sulfuric acid (20 vol
%) For 20 minutes at 70 ° C. to perform etching, followed by washing with water and dilute sulfuric acid (10 vol.
%) For 2 minutes at room temperature for washing, and after washing with water, dipping with dilute hydrochloric acid (20 vol%) for 2 minutes at room temperature for washing, and then washing with water.

Then, palladium chloride (0.5 g), stannous chloride (25 g), hydrochloric acid (300 mL), water (600
It was immersed in a solution consisting of (mL) for 10 minutes at 60 ° C. to apply a catalyst, and washed with dilute hydrochloric acid (10 vol%) and washed with water.

The molded article whose surface has been pretreated is then
Copper sulfate (7 g / L), Rossell salt (20 g / L), sodium hydroxide (5 g / L), sodium carbonate (2 g / L)
L), an aqueous solution of formalin (25 mL / L),
After soaking at 20 ° C for 30 minutes and electroless copper plating,
It was washed with water. At this time, the thickness of the copper film was about 1 μm.

After electroless plating, the molded product was used as a cathode in an aqueous solution containing copper sulfate (220 g / L) and sulfuric acid (60 g / L), and a copper plate (purity 99.9% or more) was used as a counter electrode. After electrolysis for 20 minutes at a current density of 5 A / dm @ 2 at .degree. C., it was washed with water. At this time, the thickness of the copper film is about 2
It was 0 μm.

A molded article sample in which a copper electroplating layer was formed on an electroless plating intermediate layer was thoroughly dried, and then used as a cathode in a dry box kept in a dry nitrogen atmosphere to prepare 1-ethyl-3-methylimidazo. A room temperature molten salt composed of thorium chloride (33 mol%) and aluminum trichloride (67 mol%) was used, an aluminum plate (purity of 99.9% or more) was used as the counter electrode, and the current density was 1 A / d at 60 ° C.
Electrolysis was carried out at m2 for 30 minutes. After taking out the molded product from the dry box, it was washed with water. The thickness of the obtained aluminum film was 6 μm. The obtained molded product had a metallic aluminum appearance, and the adhesion strength of the aluminum film was 1.4 Kg / cm.

Example 2 In Example 1, phenanthroline was added to the room temperature molten salt in an amount of 3 times.
The same procedure as in Example 1 was carried out except that aluminum plating was performed using a room temperature molten salt added in the amount of mmol / L. The thickness of the obtained aluminum film was 6 μm. The molded product is
Has a glossy aluminum appearance and adhesion strength of 1.2 kg /
It was cm.

Example 3 In Example 1, the panel molded product (420 × 100 m)
As m), the same procedure as in Example 1 was carried out except that an injection-molded mold was used and the electrolysis time during aluminum plating was 1 hour. The thickness of the obtained aluminum film was 11 μm, the molded product had an aluminum die cast-like appearance, and the adhesion strength was 1.5K.
It was g / cm.

Comparative Example 1 ABS front panel molded product (420 × 100 mm)
Was set in a vacuum vapor deposition apparatus, and aluminum was vapor deposited at 10 ⁻⁴ Torr. The thickness of the obtained aluminum film was 10 μm. The molded product had a metallic aluminum appearance, but as a result of a tape test, almost the entire product peeled off.

Example 4 The same procedure as in Example 1 was carried out except that an ABS foil cover molded product (outer diameter 200 mm) was used in place of the panel molded product in Example 1. The thickness of the obtained aluminum film was 6 μm, the molded product had a metallic aluminum appearance, and no abnormalities such as swelling and cracking were observed as a result of the thermal test.

Example 5 In Example 4, a foil cover molded product (outer diameter 200 m) was used.
As m), the same treatment as in Example 1 was carried out except that an injection-molded mold was used and the electrolysis time during aluminum plating was set to 1 hour. The thickness of the obtained aluminum film was 11 μm, and the molded product was
It had an aluminum die cast-like appearance and no abnormalities were found as a result of a thermal test.

Comparative Example 2 An acrylic resin-based paint containing 20% of non-leafing aluminum powder was applied to an ABS foil cover molded product (outer diameter 200 mm), and metallic coating was applied by a spray gun. Although the obtained molded product had a metallic aluminum-like appearance, cracking occurred as a result of a thermal test.

[0042]

Industrial Applicability As described above, according to the present invention, it is possible to provide a synthetic resin molded article whose surface has been subjected to an aluminizing treatment having excellent weather resistance and good adhesion.

Claims (6)

[Claims] 1. A synthetic resin molded article comprising a synthetic resin substrate, an electroless plating intermediate layer, and an electroplated aluminum layer. 2. The electroless plating layer intermediate layer is 0.3 to 20.
The molded product according to claim 2, which has a range of μm. 3. The molded product according to claim 1, wherein the intermediate layer of the electroless plating layer is an electroless plating layer made of copper or nickel. 4. The aluminum electroplating layer has a thickness of 2 to 20.
The molded product according to claim 2, which has a range of μm. 5. The molded article according to claim 1, wherein the electroplated aluminum layer is formed on the electroless plating intermediate layer with an electroplated layer of another metal interposed therebetween. 6. The molded article according to claim 3, wherein the electroplated layer of another metal is an electroplated layer made of copper or nickel.