DE2039405C3 - Process for the chemical deposition of nickel on a carrier made of synthetic resin - Google Patents

Description

For the production of a nickel plating bath in the context of the invention, parts of the surface of the resin Usable chemical nickel plating baths are not plated with nickel because that initially occurs the ascorbic acid or a salt thereof as the second adsorbed palladium to these parts by the Reducing agent and a water-soluble lead compound- frequent rinsing has been removed. For this Use as a stabilizer for the bathroom for a common reason, it happens that even experienced acidic agents or alkaline bath added, the nickel, maintenance staff not always properly nickel over lead ions, Hypophosphition as well as an organic drawn objects are generated.

Acid, a boron compound and other suitable

Compounds as a complexing and / or buffering bath according to the invention containing ascorbic acid. _lo that; from the etching and activation bath on the carrier

If, in such a chemical coating bath, palladium ion adsorbed from synthetic resin selectively contains the nickel and hypophosphite ion, palladium-reduced before the hypophosphite ion is initiated with the reduction ion, the hypophosphite ion causes the nickel ion to begin, so that a diffusion of the as a result of the catalytic effect d ^ s palladium-palladium ion in the whole nickel-plating bath vermetalls the following reaction: ₁₅ is prevented while that along with the carrier

Pailadium ion introduced into the coating bath from synthetic resin is accumulated or incorporated by the lead ion

_n catalyst is closed, which is one of the reaction effects of the

(H ₂ PO ₂ ) + H ₂ U > H (HO ₃ ) + 2H Hvpophosphitions counteracting catalytic

(1) has 2o effectiveness. As a result, the palladium ion loses its catalytic effectiveness. The ascorbic acid can be replaced by its salt and used in any

The desired amount of hydrogen atoms formed in this way are used
The lead ion should be adsorbed in the over metal according to the invention and activate its surface, preferably in an amount of not more so that the nickel ion is reduced and metallic nickel should be contained than 10 ppm, because if it is too large, as follows is deposited: amount of lead ion the reducing power of the

Hypophosphitions is lowered. The coating

Ni ⁺⁺ + 2H - »■ Ni -f 2H ^ (2) bad can be acidic or alkaline. Preferably has

30 it has a pH of 3 to 10. The per unit of time from

The nickel metal precipitated in this way in the bath decreases in the amount of nickel which then acts as a catalyst for reaction (1), so that the pH value drops below 3. The optimum working temperature continues during the formation of the nickel coating ;; Plating bath needs because of its ascorbic stride. To form a nickel coating, the acid content must not be changed, but can be applied to a metal that catalytically has the same value in reaction (1) as in the usual baths,
is ineffective, must therefore be used to deposit the nickel. In the context of the invention, etching solutions

can be used on the inactive metal in a substitution reaction that amounts to 100 to 900 cm ³ /! concentrated or an electroplating process already nickel H ₅ SO ₄ , 0 to 200 cm ³ / l phosphoric acid, 900 to be present. 100 cm ³ / l water, 5 to 300 g / l chromic anhydride,

Such an electroplating process is calculated as CrO ₃ , and contains 0.05 to 5 g / l of a palladium but not on a support made of a synthetic resin, calculated as Pd. They contain advance because this is a poor electrical conductor, preferably 400 to 900 cm ³ / l concentrated H ₂ SO ₄ . The resin must therefore be subjected to an activation 0 to 100 cm ^f / l phosphoric acid, 600 ^{to 100 cm 3} / l treatment in which there is a catalytic water, 5 to 30 g / l chromic anhydride, calculated effective material, e.g. B. Palladium metal, adsorbed, 45 as, CrO ₃ , and 0.2 to 5 g / l of a palladium salt, bedas in the subsequent deposition of the nickel counts as Pd. The chromic anhydride can be replaced by potassium dichromate, which acts as a catalyst and nuclei. The palladium salt forms. If the palladium metal adsorbed on the palladium chloride, palladium sulfate _{or sodium resin during activation is palladium chloride [Na 2 PdCl 4} ] from the resin.

peeled off when immersed in the plating bath 50. The nickel bath can, for example, 1 to 18 g / l of one becomes, or when immersing the resin in the nickel salt, calculated as Ni ion, 3 to 40 g / l of one Coating bath on the resin still a remainder of the palla-phosphite, calculated as hypophosphite ion, 5 to Activating solution containing dium adheres because the resin contains 100 g / l of an organic acid, 1 to 50 g / l of an not enough with water that has been rinsed, and ascorbic acid-like compound, calculated as the solution in the whole coating bath disperses 55 ascorbic acid, and 1 to 10 m / lg of a lead salt, is formed in this way in the coating bath calculated as lead ion, contains and contains preferred Palladium catalytically active germs, wise 2 to 8 g / l of a nickel salt, calculated as so that the reactions given above bring about Ni-ion, 5 to 18 g / l of a hypophosphite, calculated out and nickel in the coating bath as hypophosphite ion, 10 to 30 g / l of an organic is felled. If this precipitated nickel in the 60 acid, 10 to 30 g / l of an ascorbic acid compound, If resin adheres, it forms on the resin one under- calculated as ascorbic acid, and 2 to 7 mg / 1 one broken nickel plating. When too much palladium in lead salt. The baths should have a pH value of 3 to 10, the coating bath is introduced, it causes a preferably 4 to 9 have. The nickel salt can continued precipitation of nickel until the bath of nickel sulfate, nickel chloride or the like. Be. The HypoNickel impoverished and can decompose completely. An example of 65 phosphite is sodium hypophosphite. If one, in order to avoid this phenomenon, the As ascorbic acid compound one can use ascorbic resin after activation too often with water acid, sodium ascorbinate or the like. Use. the SDÜlt. When the resin is immersed in the organic acid consists of a short chain

Monocarboxylic acid, ζ. Β. acetic acid, propionic acid and butyric acid, a salt of a ^r cruzkettigen monocarboxylic acid, a Dicarbonslure, z. B. malonic acid, succinic acid or adipic acid, a dicarboxylic acid salt, a tricarboxylic acid, e.g. B. the .Citric acid, a tricarboxylic acid salt, an oxyicarboxylic acid, z. B. glycolic acid, lactic acid, malic acid and tartaric acid, an oxycarboxylic acid salt, an aminocarboxylic acid, e.g. B. the aminoacetic acid or aminopropionic acid or an aminocarboxylic acid salt. For example, the sodium, potassium, ammonium and the like salts of these acids can be used. The lead acid is lead nitrate or lead acetate. Ammonium chloride, borax and the like can be used together with the above-mentioned organic acids.

The advantages achieved by the invention are in particular that in addition to reducing the The number of baths and a number of washing processes that have to be carried out between baths are dispensed with Nickel bath is stable and the plastic surface is provided with a solid nickel coating.

For a better understanding of the invention, exemplary embodiments are described below:

example 1

Test pieces measuring 65 × 40 × 3 mm were degreased with an alkali and rinsed with water. The examinees consisted of an acrylonitrile butadiene styrene resin (ABS resin) suitable as a coating carrier. The split Specimens were immersed in an etching solution at 60 ° C. for 15 minutes for etching, as follows Composition hold:

Concentrated H ₂ SO ₄ 500 cm ³ / l

Water 500 cm ³ 1

Chromic anhydride 15 g / l

Palladium chloride 0.5 g / l

The etched specimens were rinsed with water. Then some of the specimens were immersed for 5 minutes at 40 "C in 200 cm ^{3 of} a novel chemical coating bath so that a nickel coating was formed on the specimens. The coating bath according to the invention had the following composition:

Nickel sulphate 20 g / l

Sodium hypophosphite 15 g / l

Adipic acid 10 g / l

L-ascorbic acid c 10 g / l

Lead nitrate 5.5 g / l

pH (adjusted with NaOH) ... 6.0

The usual bath thus had the same composition as the bath according to the invention, but contained no L-ascorbic acid and no lead nitrate.
The following results were obtained:
The etched test specimens immersed in the bath according to the invention were evenly coated with nickel over their entire surface. The bath remained clear during the treatment. In contrast, test specimens immersed in the usual bath had punctiform nickel deposits on their surface. A dark precipitate formed in the bath during treatment.

Example 2

The procedure according to Example 1 was repeated. However, an etching solution and a conventional and one according to the invention: s nickel plating bath used with the following characteristics:

Etching solution

Concentrated H ₂ SO ₄ 800 cm ³ / l

Water 200 cm ³ / l

Chromic anhydride 10 g / l

Palladium sulfate 0.5 g / l

Temperature of the solution 40 ⁰ C

Immersion time 5 min

Chemical nickel plating baths

Usual Invention bath appropriate bath Nickel sulfate 16 g / l 16 g / l Sodium hypophosphite 11 g / i 11 g / i Citric acid 6 g / 1 6 g / l borax 2.5 g / l 2.5 g / l L-ascorbic acid none 3 g / l Lead acetate no 7 mg / 1 pH value of the bath (with NaOH adjusted) 8.0 8.0 Bath temperature 30 ° C 30 ⁰ C Immersion time 3 min 3 min

For comparison, the other test specimens, which had been etched and then rinsed with water, were ^{immersed in 200 cm 3 of} a conventional chemical plating bath for the same time and at the same temperature as in the test described first, so that a nickel coating was formed on the test specimens. This usual bath had the following composition:

Nickel sulfate, 20 g / l

Sodium hypophosphite 15 g / l

Adipic acid 10 g / l

L-ascorbic acid -

Lead nitrate -

pH value (adjusted with NaOH) 6 0

The test specimens treated in the bath according to the invention were initially etched on the whole A uniform nickel coating. Dus bath remained immersed during the treatment Test specimen clear. The test specimens treated in the usual bath had point-like shapes on their surface Deposits of nickel deposited from the bath. This bath also remained during the treatment of the immersed test specimens clear.

Example 3

The procedure was as in Example 1, but with an etching solution and an inventive and a common nickel plating bath with the following characteristics:

Etching solution

Concentrated H ₂ SO ₄ 500 cm ³ / l

Water 500 cm ³ / l

Potassium dichromate 10 g / l

Sodium palladium chloride lg / 1

Solution temperature 60 ° C

Immersion time 10 min

Rhenish nickel plating baths

Usual
bath

Bath according to the invention

Nickel sulfate 20 g / l 20 g / l Sodium hypophosphite 15 g / l 15 g / l Sodium succinate 15 g 1 15 g / l ! .- ascorbic acid none 30 g / l Lead acetate no 10 mg / 1 pH value of the bath (with 4.0 4.0 NaOH adjusted) Bath temperature 60 C 60 C Immersion time 3 min 3 min

The test specimens treated in the bath according to the invention had a uniform surface over their entire surface Nickel plating, and the bath remained during the treatment of the specimens immersed therein clear. The test specimens immersed in the usual bath had point-like nickel deposits on their surface. In the usual bath, a dark precipitate forms during the coating process.

Example 4

The procedure of Example 1 was repeated, but instead of the ABS resin, the specimens were made on polystyrene and were an etching solution, a conventional and an inventive coating bath with the following parameters are used:

At / solution

Concentrated H ₂ SO ₄ 860 cnv / l

Phosphoric acid (85 ° _o ) 50 cm ³ / l

Water 90 cm ^3/1

Sodium dichromate 17 g / l

Palladium sulfate 9 g / l

Solution temperature 25 C

Immersion time 5 min

Chemical nickel plating baths

usual
bath

Bath according to the invention

Nickel chloride 20 g / l 20 g / l

Sodium hypophosphite 27 g / l 27 g / l

Sodium succinate 16 g I 16 g I

i -. \ seorbin5, acid no 10 g / l

Lead acetate no 5.5 mg'l

pH value of the bath (with 4.8 4.8

NaOH adjusted)

Badterr.penitur 65 C 65C
Immersion time t 5 min 5 min

The following results were obtained:
The nickel deposited on the etched specimens in the bath according to the invention formed a uniform layer of nickel over the entire surface of the specimens. The bath remained clear during the treatment. On the other hand, the usual bath became nickel au; ' the etched specimens deposited in the form of punctiform deposits. This bath also remained transparent during the treatment.

Example 5

The procedure according to Example 1 was repeated. Test specimens made of polyester and an etching

solution, an inventive and a conventional coating bath used with the following characteristics:

Etching solution

Concentrated H ₂ SO ₄ 800 cm ³ / l

Water 200 cm ³ /!

Chromic anhydride 10 g / l

Palladium sulfate 0.5 g / l

Solution temperature 60 "C

Immersion time 2.0 min

Chemical nickel plating jiders

Usual bath

Invention bathroom

Nickel chloride

Sodium hypophosphite

Citric acid

Ammonium chloride
Ascorbic acid

Lead nitrate

pH value (with NaOH

set)

Bath temperature
Immersion time

60 g / l 20 g / 1

100 g / l 50 g / 1

none

no 9

50 ⁰ C for 5 min

60 g / l 20 g / 1 100 g / l 50 g / l 10 g / l

7 mg / 1

50 ⁰ C for 5 min

The test specimens treated in the bath according to the invention have one of the entire etched area even nickel coating. Clear the bath sieve during the treatment. Against it was on the examinees after the treatment in the usual bath, there was no nickel plating and it was left in the bath even a dark precipitate formed.

Example 6

The procedure according to Example 1 was repeated, but with test specimens made of polypropylene, wherein an etching solution and a coating bath according to the invention and a conventional coating bath with the following characteristics were used:

Etching solution

Concentrated sulfuric acid 500 cm ³ / l

Water 500 cm ³ / l

Chromic anhydride 15 g / l

Sodium palladium chloride lg / 1

Temperature of the solution 8G ⁰ C

Immersion time 30 min

Chemical nickel baths

Usual bath

Unit of the invention bath

Nickel sulfate 50 g / l 50 g / l

Sodium hypophosphite 20 g / l 20 g / l

Sodium acetate 10 g / l 10 g / l

Ascorbic acid no 30 g / l

Lead acetate none 5 mg 1

pH value (with NaOH 5 5

set)

Bath temperature 50 "C 50 ⁰ C

Immersion time 5 min 5 min

The test specimens treated in the bath according to the invention had a nickel coating over their entire surface. The bath remained clear during treatment. In contrast, those treated in the usual bath were Test objects only on about half of their area: with

609 683/126

9 10

5! InSr ⁰ NH ^08en h | ^{And, SiCh in the bath formed the one treated in the bath of the present} invention

dark precipitation. _{Examinees had a whole on him Oberflftche}

Example 7 Uniform Nickel Plating. The bathroom stayed on

n, v Δ, ΚΛ-t, · α ο · · ι ·, j · j, ^the treatment is clear. The usual bathroom became

_W Ü ^b f ^wise example 1 was repeated, 5 no nickel was deposited, but rather it was formed

however, an etching solution and a common and a dark precipitate
A coating bath according to the invention with the following characteristics was used:

Etching solution experiment 1

Concentrated H ₂ SO ₄ 500 cm ^a / l

Water 500 cm ³ / l. ^{For the v} . ^He was g'eich performed an attempt

Chromic anhydride 15 _g / l ^m the procedure was followed as in Example 5, but with

Palladium chloride, 0.5 g / l of a customary bath A ₁ , a bath B ₁ , the set up

The temperature of the solution was 60 ° C by adding 10 g / l sodium L-ascorbate to a

Immersion time 15 min. ¹⁵ bath ^A i were added, a bath C ₁ which was prepared

was added by adding 3.7 mg / l lead acetate to a bath Ai

Chemical nickel plating baths were added, and a bath D ₁ according to the invention.

Each etched specimen was used ^{to form a coating}

Usual invention during a predetermined ⁷ "it h '""· 5 min

Bath according to the bath so in 200 cm ^{3 of} the bath covered in the next

^l - DUT immersed under the same conditions

Nickel chloride 20 e / 1? 0 * / l T ^ ^M T ^k ° ^{"nth therefore after} treatment, each

Sodium hypophosphite 15 ~ [ ₅ ] depends on the state of the nickel

Adipic acid ^P 5 g 5! ₂ ^ ^be . ^rzu f ^s _t '^ the change in the appearance of the

Sodium -.- Ascorbate _ {n! ' ^{25 bath} «^ set. For treatment in each of the baths

Lead acetate _ 37L / 1 7Λ ^ ", ^{& 1ζ Of twenty} 8 test items P ₁ to P ₂₀

pH value (adjusted 6 t '® ⁽ _} ^X - ^{40 x} J ^mm ] ™ ABS resin made,

A satisfactory result was obtained with NaOH) ^aem

Bath temperature 60 ^C C 60 "£ Γ" ^Γ T * ^d ™ ^erfindun obtained gsgemäßen Bad _d1. the

Immersion time 5 min 5 min ^Eir S ^e bn. _S se are in Table I below

J min 5 min stated.

Table 1

Used baths

Bad A ₁

Exposed area percentage,%

Change in the appearance of the bathroom

Bad B ₁

Exposed area percentage,%

Change in the appearance of the bathroom

Bath C ₁

Exposed area percentage,%

Change in the appearance of Hades

Bad D ₁

Exposed area percentage,%

Change in the appearance of the bathroom

P ₆ to P ₁₅ P ₁₆ to P _{! 0}

O 0 0 0 I. j ι k. k. k. Zs. I.
I. I.
I. I.
! O / I. / I. I. Zs. / I. /
/ I. I. I. I. I. I. I. I. O 0 20th 80 50 20th I. k. k. k. k. k. Zs. I.
I. 100
k. 100
k. 100
k. 100
k. 100
k. 100
k. 100
k.

When specifying the coated surface portion of the value states of 0%, that the specimens were not covered or only slightly with nickel, and the value of 100 ° _o that the iPrüflinge were covered over their entire Hache evenly with nickel Values

χ? ", ² ? '?: ⁵⁰ ° ^{/ o b2w} - ¹⁰⁰ % 8 ^just ""g ^ hr the area portion coated with 6, nickel.

When specifying the change in the appearance of the bathroom, the specification states <> L «that no changes

tion occurred, and the indication "Zs" that the bath decomposed.

With / it is indicated that the examination because of the decomposition of the bath could not continue. Table 1 shows:

(1) Bad A ₁ :

The test specimens! P ₁ to P ₄ were not or only very slightly coated with nickel. When immersing P ₄

the bath was decomposed and the test could not be continued.

(2) Bath B ₁ :

The sample P ₁ was hardly covered with nickel and the bath was decomposed, so that the test could not be continued.

(3) Bath C ₁ :

The specimens P ₁ and P ₂ were hardly covered with nickel. The test specimens P ₃ to P ₅ were coated with nickel over 20%, 80% and 50% of their area. The specimens P _G to P ₁₅ were coated with nickel over an average of 20% of their area. When P _{15 was} immersed, the bath decomposed so that the test could not be continued.

(4) BaUD ₁ :

All test items P ₁ to P ₂₀ . were evenly coated with nickel over their entire surface. The bathroom did not change its appearance during the entire test.

Example 8

The procedure was as in Example 1, but with one etching solution and one standard and one Coating bath according to the invention, which had the following characteristics:

Etching solution

Concentrated H, SO ₄ 800 cm ³ /!

Water "200 cm ³ zl

Chromic anhydride 10 g / l

Falladium sulfate 0.5 g / l

Solution temperature 50 "C

Immersion time 10 min

Table 2

Chemical nickel plating bath

Usual Invention bath appropriate bath (A ₂ ) (D ₁ ) Nickel sulfate 16 g / l 16 g / l Sodium hypophosphite 11 g / l 11 g / l Citric acid 10 g / l 10 g / l borax 6 g / l 6 g / l Sodium L-ascorbate Og / 1 7 g / l Lead nitrate Og / 1 7 mg / 1 pH value (adjusted 9 9 with NaOH) Bath temperature 40 C 40 ¹ C Immersion time 3 min 3 min

The results show that no nickel deposited on the etched pieces from the usual bath and the appearance of the bath has not been changed, d. that is, the bathroom remained clear. From the invention The bath was evenly deposited nickel over the entire surface of the etched specimens, and the bath did not change its appearance, but remained clear.

Attempt 2

For comparison, the procedure according to Example 6 was repeated, namely with bath A ₂ , a bath B ₂ , which had been prepared by adding 7g 1 of sodium L-ascorbate to a bath A _a , a bath C ₂ , which by Addition of 7 mg / 1 lead nitrate had been made to a bath A ₂ , and a bath D ₂ . In this comparative experiment, too, each of the baths was used in an amount of 200 cm ³ _{, and twenty specimens (P 1} 'to P ₂₀ ') were prepared for treatment in each of the baths.

The results obtained are shown in Table 2.

30th

Used baths

Test item Pi ' P _s ' to P ₃₀ '

Bad A ₂

Coated surface area,

Change of bathroom

Bad B ₂

coated surface area,

Change of bathroom

Bad C ₂

Coated surface area,

Change of bathroom

Bad D ₂

Coated surface area,
Change of bathroom
ng - not checked.

0 'k.

0 Zs.

1;.

100

k.

0 k.

0 k.

0 k.

n. g. n. g.

0 k.

100
k.

k.

100
Jc.

0 k.

100
k.

n. g.

n. g.

100 k.

Table 2 shows that hardly any nickel was deposited on the etched specimens P ₁ 'to P _{4 ' from baths A 2} and C ₂ , and the baths did not change their appearance. These baths were therefore not used again. When the test specimen P ₁ 'was treated in the bath B ₂ , this decomposed with the formation of a dark precipitate and no nickel was deposited on the test specimen. _{The bath D 2} according to the invention was very stable and led to the uniform deposition of nickel over the entire area from P ₁ 'to P ₂₀ ' without changing the appearance of the bath.

Example 9

The procedure was as in Example 1, but an etching solution and a conventional and a

13 14

Coating bath according to the invention with the following characteristics: The usual bath hardly turned into nickel

values used: deposited on the etched specimens and formed

Etching solution ^s ' ^{cn m} the B ^a ^ eir · dark precipitate. From the

Concentrated H ₂ SO ₄ 500 cm ³ / l bath according to the invention became nickel evenly

Water "... 500 cm ³ / l ⁵ deposited on the surface of the etched test specimen,

Potassium dichromate 10 g / l whereby the bath remained clear.

Sodium palladium chloride

(Na ₂ PdCl ₄ ) 1 g / 1

Solution temperature 60 ° C

Immersion time 10 min ¹⁰ attempt 3

Chemical nickel plating baths

Customary invention I _n the manner indicated in Example 7 was a

ΪαΊ s = ^{moderate ßad} comparison test carried out with a

- - '15 usual bath A ₃ , a bath B ₃ , which by addition

Nickel sulfate 20 g / l 20 g / l of 30 g / l sodium L-ascorbate to a bath A ₃

Sodium hypophosphite 15 g / l 15 g / l had been _{prepared, a bath C 3} , which by adding

Sodium succinate 15 g / l 15 g / l set of lead acetate has been made up to a bath A ₃

Sodium i.-ascorbinate was 0 g / l 30 g / l, and a bath D ₃ according to the invention. In this

Lead acetate 0 g / l 5 mg / 1 20 experiment was as in the other experiments each

pH (with H ₂ SO ₄ 4 4 bath in an amount of 200 cm "and were used

set) for treatment in each of the baths twenty test specimens

Bath temperature 60'C 60 ^c CP / 'to P ₂₀ ". The results obtained are

Immersion time 3 min 3 min indicated in Table 3.

Table 3 Test item P ₂ " P ₃ " P ₄ " F ₆ "to P ₂₀ " P ₁ " Used bath / / / / Bad A ₃ 20th Zs. / / / Exposed area percentage,% k. Change of Eades / / / / Bad B ₃ 100 Zs. / / I. Exposed area percentage,% k. Change of bathroom 0 0 0 0 Bad C ₃ 0 k. k. k. k. Exposed area percentage,% k. Change of bathroom 100 100 100 100 Bad D ₃ 100 k. k. k. k. Exposed area percentage,% k. Change of the bath

The results shown in Table 3 are similar to those obtained in Experiments 1 and 2.

Table 3 shows:

Nickel was deposited from bath A ₃ on about 20 ° _o the area of P ₁ ". The bath decomposed while P ₂ " was immersed in it.

From bath B _{3 , nickel was deposited evenly over the entire area of P 1} ". The bath became cloudy. During the immersion time of P 2", the bath decomposed.

From bath C ₃ , nickel was deposited in the form of fine points on each of the test specimens P ₁ ″ to P ₂₀ ′. The bath did not change its appearance.

/ 'us the bath D ₃ was evenly on the nickel

The entire surface of each of the test specimens P ₁ ″ to P ₂₀ ″ ^from S ^e ″ was separated. The bath remained very clear.

Example 10

Test specimens used: styrene resin plates, 45 X 40 X 1.5 mm

Etching solution

Concentrated H ₂ SO ₄ 860 cm ³ / l

Phosphoric acid 50 cm ³ / l

Water 90 cm ³ / l

Potassium dichromate 17 g / l

Palladium sulfate 9 g / l

Solution temperature 25 ° C

Immersion time 5 min

Chemical nickel plating baths

Usual Invention bath according to. bath (A ₁ ) (D ₁ ) I nod chloride 20 g / l 20 g / l Sodium hypophosphite 27 g / l 27 g / l Natrhiirijuccinate 16 g / l 16 g / l Sodium L-ascorbate Og / 1 10 g / l Lead acetate Og / 1 5.5 mg / 1 pH value (adjusted 4.8 4.9 with H ₂ SO ₄ ) Bath temperature 65 ° C 65 ° C Immersion time 5 min 5 min

The following results were obtained: The usual bath became nickel all over Surface of only a few test objects deposited, which in the

first part of the coating process. After the start of the coating process, formed a dark precipitate in the bath. In contrast, the bath according to the invention became evenly nickel deposited on the entire surface of each of the specimens used. The bathroom remained clear.

Attempt 4

For comparison, the procedure of Example 8 o was repeated, namely with a bath A ₁ , a bath B ₄ , which had been prepared by adding 10 g / l sodium L-ascorbate to a bath A ₄ , a bath C ₄ . which had been prepared by adding 5.5 mg / l lead acetate 211 to a bath A ₄ , and a bath D _4. As in the experiments described above, each bath was used in an amount ν> n 200 cm ¹ and was used for the treatment Twenty test specimens were made in each of the baths.

The results are in the table below specified:

Table 4

Test item P, '" P, '" P ₁ '" Pj '"to P», "' Used bath P ₁₁ " Bad A ₄ 100 100 / I. Exposed area percentage,% 100 k. k. Zs. I. Change of bathroom k. Bad B ₄ 100 I. I. I. Exposed area percentage,% 100 k. Zs. I. I. Change of bathroom k. Bad C ₄ 50 50 50 50 Exposed area percentage,% 50 k. k. k. k. Change of bathroom k. Bad D ₄ 100 100 100 100 Exposed area percentage,% 100 k. k. k. L. Change of bathroom L.

The results given in Table 4 are similar to those obtained in Experiments 1 and 3.

From bath A ₄ , nickel was deposited over the entire surface of the first three test specimens P ₁ '"to P ₃ '". During the immersion time of the fourth test specimen P ₄ '"in the bath, the bath decomposed with the formation of a dark precipitate.

From bath B ₄ , nickel was deposited over the entire surface of the first two test specimens P ₁ '"and P ₂ '". The bath decomposed during the thawing time of the third test specimen P ₃ '".

From bath C ₄ , nickel was deposited on approximately 50% of the area of all test specimens P ₁ '"to P _2n '". The bathroom remained clear.

In contrast, from the bath D ₄ according to the invention, nickel was deposited evenly over the entire surface of all test specimens P 1 '"to P ₂₀ '". The bath remained very clear and showed no sign of decomposition.

Comparative experiments

Comparative tests were carried out between the method according to the invention and US Pat. No. 3,437,507 accomplished.

In the process according to the US-PS two stages are used, namely etching with palladium chloride containing sulfuric acid solution and chemical, electroless deposition of nickel from a Nickel bath.

To carry out the experiment, the following compositions were chosen, which are Example 1 of US Pat (Etching solution) and the description of column 4, line «65 to column 5, line 6 correspond.

1. Etching solution:

Sulfuric acid 19.95 percent by weight

Palladium chloride 0.05 percent by weight

Deionized water . . 80 percent by weight

Temperature 70 "C

Treatment time 2 min

2. Nickel bath:

Nickel sulfate 30 ρ "■

Natriuirihypophosphii 10 g

Citric acid 15 g '

pH regdune to pH '> 0 with NaOH Temperature 65 (

Treatment time different

The attempt according to the guideline is undesirable Example 1 of the description, carried out g. Thieves-

609 683 M6

Levels of action, formulations and test conditions were the following:

1. Etching or pretreatment solution:

Sulfuric acid 500cm ^a / l

Deionized water 500 cm ³ / l

Chromic acid 15 g / l

Palladium chloride 0.5 g / l

Temperature 60 ° C

Treatment time

60 ° C 15 min

2. Nickel bath:

Nickel sulphate 20 g / l

Sodium hypophosphite 15 g / l

Adipic acid 10 g / l

1-ascorbic acid 10 g / l

pH aaTöV adjusted with NaOH

Temperature .-

Treatment time

Experimental method: Two 200 ml baths were made using the

15 determined.

Co.)

Cycolac EP ₁ an area of 50 cm'-

Vers uichserg :: bnissti

Expires according to US-PK 34 37 507

Treated floods

By separation
covered area
State of the solution
liability

5min Ui 3h 12h 24h 0 1% 10% 90% 100%

stable

lots of bubbles and

bad adhesion

Test results

Method according to the invention

Treated panels 1. 2 ·

Treatment time 5 min 5 min

Area covered by deposition 100% state of the solution stable

Liability ^

100% stable 24h 30%

stable poor adhesion

4th plate

3. 5 min

100% stable good

24h 30%

stable

bad

liability

24h 20%

decomposed

bad

liability

4. 5 min

5. 5 min

ICO% stable good

100%

stable good

10. 5 min

100% stable good

Claims (3)

Palladium ions are reduced and this bath becomes patent claims: quickly consumed. If the activated carrier comes together with the one adhering to it, unnecessarily 1. Process for the electroless deposition of reduced, very finely divided palladium metal in one Nickel on plastics, with the plastics 5 chemical coating bath, so you get on the Surface with a chromium-sulfuric acid carrier a nickel coating with a rough surface, holding etching or pretreatment solution active after treatment in the sensitizing bath is fourth and nickel is electrolessly discharged from a bath; the carrier, as mentioned, is an activation bath that is exposed to a reducing agent and one that consists of a dilute solution of Contains lead salt, thereby marked, o Palladium chloride consists of hydrochloric acid (Journal et that "Metal Finishing" 53 [1955], No. 8, p. 61). The , _Λ . _,,. ,. _ ",. ,,. , Tin (II) ion, which from the Sensibilisierur.gsbad on (a) additionally containing a Palladiumsak _the \ 4 _{EER adsorb} ICRT has been reduced in the support, the palladium ion in ATZ or pretreatment solution and contained Eintauchet (b) an ascorbic acid, or an ascorbic acid activating bath, the nickel bath containing palladium ion to fine salt is used. ^. ^ _{PalladiumiTietall) which then fes} t on the carrier 2. The method according to claim I ₁ thereby marked is adsorbed. If too little palladium metal shows that a 100 to 900 ml / l concentrated is adsorbed, an incomplete sulfuric acid, 0 to 100 ml / l phosphoric acid, chemical nickel coating is obtained. If, on the other hand, un-900 to 100 ml / l water, 5 to 300 g / l chromic acid-20 desired palladium inside together with the carrier anhylride, calculated from CrO ₃ , and 0.05 to 5 g / l in a chemical ·; Nickel plating bath introduced palladium iium salt, calculated as Pd-containing etch, forms the palladium ion, catalytically active iÖMJ -g is used. Germs, so that nickel is deposited in the bath or 3. The method according to claim 1 or 2, characterized in that the bath is suspended or, in some cases, decomposed in that the palladium salt is palladium-25 and can therefore not be reused,
chbrid, palladium sulfate, or sodium palladium- Das. Nickel plating bath can be used in addition to the well-known chi: irid vs. Besiandteile contain additions of 0.007% lead acetate <■ method according to one of claims 1 to 3, (FR-PS 15 51 348). characterized in that a 1 to 18 g / l. This method has the disadvantage that there are four Nickel salt, calculated as Ni, 3 to 40 g / l hypo- 30 different baths needed and between the einphosphit, calculated as hypophospition, 5 to individual steps, numerous washing processes with water 10 (1 g / l of a carboxylic acid, 1 to 50 g / l of a necessary * ind for a perfect coating Ascorbic acid compound and 1 to 10 mg / 1 lead and a longer period of use of the bath to total, calculated as a Pb-containing nickel bath. is used. 35 nickel coatings with a bath temperature of about 95 ° C., as given in "Metal Finishings August 1955, p. 61" scroll on cooling to room temperature since their thermal expansion is greater than that of the wearer. In US-PS 34 37 507 a method is described The invention relates to a method for electroless, in which plastic! Rager with nickel without Deposition of nickel on plastics, whereby the sensitization n * it tin (II) chloride coated who-Kvmsiütofffläche with a chromium-sulfuric acid. The activation of ABS plastic takes place with containing AU or pretreatment solution active 45 aqueous., sulfuric acid and palladium chloride devated is and nickel is electroless from a bath-enduring solution, with the object either parted «!! is that a reducing agent and a lead previously etched with an aqueous chromic acid solution contains salt. and then with a sulfuric acid Pd salt solution For electroplating a synthetic resin object or treated with this solution only and afterwards several pretreatment measures are required - the nickel coating is aged for 24 hours. This Hch, so that the resin object is electrically conductive method, while avoiding the use of the multitude will. of the different baths used in the other procedure For an electroless Nicketa! "Separation on plastic, however, it has the disadvantage that a material is known to immerse a carrier made of synthetic resin, initially formed on the carrier, into an etching solution which is made of chromium-sulfur and the bath is not stable because the acid phenomenon exists here (magazine "Metal Finishing" 60 [1962], the " Zersetzung des coating baths" in observer 6, p. 71; 62 [1964], book 11, p. 53) .Then is th. If he is then in a sensitizing bath from a De: r invention is based on the task of a dilute solution of tin (II) chloride immersed in hydrochloric acid process for the formation of chemical nickel. This bath must be such that 60 puffs can be developed using only two baths, on the carrier tin (II) ions in such an amount avoids decomposition of the coating bath are adsorbed that they reduce the Palla and at the same time a permanent nickel coating dium ions guaranteed by the subsequent activation. to be attached to the carrier are sufficient. This is achieved according to the invention by If too few tin (II) ions are adsorbed, 65 that a) an additionally containing palladium salt forms an incomplete coating. If there is too much caustic or pretreatment solution and b) an ascorbic tin (It) ion Acid or a nickel chloride containing aluminum, corbic acid salt get into the activation bath unnecessarily too many of the bath contained therein is used.