DE1621077A1 - Process for the deposition of metal coatings - Google Patents

Description

FARBENFABRIKEN BAYER AG 1621077

LEVERKUSEN. Bayerwerk patent department

G / Sh

Process for separating metal coatings

The invention is a method for producing a Metal coating on a plastic containing styrene.

There has been a method for producing metal coatings on thermoplastics by treating the plastic with a pickling agent and applying an electrically conductive layer with subsequent galvanic deposition of a metal coating found, which is characterized by that, one uses a styrene-containing plastic that 0.1 to 50 percent by weight of a solid, finely divided inorganic substance with a particle size of 0.1 to 2 / u contains in homogeneous distribution.

Suitable for the process are homopolymers and copolymers of styrene and its alkyl derivatives with other monomers copolymerizable therewith, e.g. B. Diene, acrylic and metacry! Compounds. Examples of suitable styrene-containing plastics are mixed "and graft polymers of styrene and butadiene, ¹ styrene and acrylonitrile, styrene, acrylonitrile, and methacrylic acid, and acrylonitrile-butadiene-styrene polymers (ABS polymers). Especially suitable are graft polymers of styrene ge and acrylonitrile and their alkyl derivatives on polybutadiene. and mixtures of these graft

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polymers with copolymers of the type mentioned above, ζ. Β. Styrene-acrylonitrile copolymers. These polymers are all known

The inorganic finely divided solid substances are these polymers by known methods, for. B. by incorporation added on mixing mills or in the Banbury mixer. These finely divided inorganic substances are required in amounts of 0.1 to 30 percent by weight, preferably 0.5 to 20 percent by weight, based on the polymer. Your particle size should be between 0.1 and 2 / U, preferably 0.2 to 0.6 / U. Examples for finely divided inorganic substances are inorganic pigments such as titanium dioxide (rutile and anatase) and zinc oxide, titanium dioxide is preferred.

By adding the finely divided inorganic substances it is possible to metallize a whole range of polymers in such a way that that the metal coating has a high adhesive strength. In other cases, the adhesion of the metal coating becomes critical improved.

The methods of producing metal coatings on plastics are known per se. The general procedure is as follows; The plastic surface is cleaned and then pickled or "chemically roughened", usually with one Pickling bath modified with chromosulfuric acid or with phosphoric acid Contains chromosulfuric acid. Metal nuclei are then formed on this roughened surface

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deposited, for example by treatment with tin (II) chloride and silver nitrate solution. These deposited metal nuclei make the application of an electrically conductive layer possible. This layer can e.g. B. be a copper plating that one can be produced if you put the treated plastic in a

Copper salt solution immersed «the one complexing agent and contains a reducing agent. On the electrically conductive one Copper layer can then be used in well-known and customary catfish a metal coating can be deposited galvanically. This metallization process is known per se and is » described for example in "Metal Finishing", November 1964, pp. 52-59. Suitable baths for the preparation of the coating are customary in the trade and are described, for example, in the company publication of the Schering AG Berlin department Electroplating "NOVIGANTH" process for electroplating of plastics 4th edition. Further literature: Galvanoteohaik Vol. 56, No. 7, pages 390 to 4-18 (1965).

example 1

Using a mixing roll mill, 10 parts by weight of zinc oxide are rolled into 100 parts by weight of a styrene-acrylonitrile copolymer at a temperature of 160 ^{° C.} The Siyrene-acrylonitrile copolymer contained about 70 percent by weight of styrene and 30 percent by weight of acrylonitrile and has an intrinsic viscosity of 0.80. (Measurement in dimethylformamide as solvent at 20 ^° C.). The zinc oxide is characterized by a particle size distribution between 0.1 and ² »° px. After the homogeneous distribution of the zinc oxide in the roller head

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BATH

the same is drawn off and then granulated. the end The granulate is made into test panels with a wall thickness of 4 mm by injection molding. The further treatment of the specimen surfaces takes place in four steps.

1) The test panels are immersed in a pickling solution with the following composition for a period of 8 minutes? 1500 g concentrated sulfuric acid d (20 °) = 1.85 g / cm ⁵ ,

^ 25 cm of desalinated water and 50 g of chromium trioxide. Bath temperature 6O ⁰ C.

2) After the "roughening", the test specimens are washed with demineralized water and then the surface is sensitized. This is done by immersing the roughened plates for two minutes in an aqueous tin (II) chloride solution with the following composition: 35 g tin (II) chloride, 50 cm conc. 35% hydrochloric acid and 1000 cm of deionized water (bath temperature 2O ⁰ C). After repeated washing, the surface is activated in the third stage, which is carried out as follows?

3) For a period of 2 minutes, the test specimens are immersed in an ammoniacal silver nitrate solution, the following composition has 3g silver nitrate, 10 cm conc. Ammonia solution d (20 °) = 0.9 g / cm and ⁵ 1000 cm ⁵ demineralized water (bath temperature 20 ⁰ C). After repeated rinsing with demineralized water, chemical copper plating then takes place,

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4) Application of the conductive Kupferschient ie, chemical copper plating is carried out according to the Noviganth "" written "in the company publication of the company Schering AG, Berlin, 4 * Edition, - procedures.

After completion of the chemical copper plating - on the surface of the molded case, a copper layer of approximately 0.5 / u applied - the Kupferleitschicht u is amplified by electrochemical plating 40>.

The adhesive strength of the metallic coating on the plastic surface is determined on the test specimens treated according to the above method. The test is based on DIN standard 40802s. The apparatus we use to measure the adhesive strength data was described in "Metallic coatings on plastics" 1966, Carl-Hanser-Verlag Munich, page 37 and ff. The adhesive strength value determined using this method is shown in Table 1 under 1.

Example 2

Instead of the zinc oxide used in Example 1, - to 100 parts by weight of styrene-acrylonitrile copolymer - 10 parts by weight Titanium dioxide is used, which has a particle size distribution of 0.1 to 1 / U. Otherwise, the procedure in Example 1 is followed. The resulting adhesive strength data are listed in Table 1 under 2.

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Comparative example A '

In contrast to Examples 1 and 2, there is no addition of an inorganic filler here. The further treatment of the surface of the test panels consisting of pure styrene-acrylonitrile copolymer is carried out in the same way as already described in Example 1. The resulting adhesive strength of the copper coating is given in Table 1 under A.

Comparative example B

If the zinc oxide addition of Example 1 is replaced by the same Amount of copper powder that has a grain size distribution from 0.1 to 20 / u has, so it results, after further processing as in Example 1 describes bond strength data presented in Table. are shown under B.

^{Table 1} Comparative

Example example example

Styrene-acrylonitrile copolymer ^{1 AB}

70:30 V = 0.80 parts by weight. 100 100 100

Zinc oxide, grain size
0.1 - 2.0 / U parts by weight. 10 - -

Titanium dioxide, grain size

0.1 - 1.0 / U part by weight. -. 10

Copper powder, grain size

0.1 - 20 / U parts by weight. - - Adhesion strength in kp / inch.

based on DIN 40802.: 1.94 1.73 1.35 0.80

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Example 3

By means of a mixing roll at a temperature of 16O ⁰ G in 100 Gewiehtsteile a Aerylnitril-butadiene-styrene graft polymer, having the following Bruttozue & mmensetzung, 17.5 percent by weight of polybutadiene, 60 weight percent styrene, and 22.5 weight percent acrylonitrile, rolled 4 parts by weight titanium dioxide. After the granulation, test plates with a wall thickness of 4 mm are again produced from this mixture. The further treatment takes place in principle according to the same process as was already described in Example 1. The roughening time was reduced to 5 minutes. The resulting adhesive strength value is shown in Table 2 below. 3 listed ..

Comparative Example C

The experiment of Example 3 is repeated, but no titanium dioxide is added during the roller treatment. The follow-up the pure ABS test specimen is carried out in the same way as already described in Example 1. When measuring the Adhesion strength results from the value listed in Table 2 under G.

Table 2 Example 3

ABS graft polymer consisting of % 17.5% by weight polybutadiene, 60% by weight styrene, 22.5% by weight. fo acrylonitrile wt.

Titanium dioxide, grain size 0.1 2.0 / U Weight TIe.

Adhesion strength in kp / inch based on DIE 40802

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100

Comparative Example C

100

2.6

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Example 4

In Ahalogiizufe Example 1 are on a mixer to 100 Ge · ^ Most important of the ASS graft polymer 4 * 0 parts by weight ; ! Added titanium dioxide. The ABS graft polymer has the following Composition based on: 15 * 0 percent by weight polybutadiene, 49 »0 percent by weight ^ -jfiethjästyroly It weight percent styrene as well

25 percent by weight \ acrylonitrile, after the production of test panels The following machining process is used with a 4 "mm square Dife specimens are carried out during a period of time of 9 minutes, immersed in a pickling solution, the following Additional information?

475 cm ⁵ H ₂ S%; conc * d (20 °) = 1, a5 ^ g / cm ³ , 192 cm ³ H ₅ PO ₄ conc. d (20 ^p ) = 1.7Qg) ^ r i desalinated water 590 cm ^ and 27.7 g of chromium trioxide. ' ^r ■ · /:

The shaped bodies are then further treated according to the example i »The bond strength test results in a value From 1.90 vfcp / inch /> ;

Comparative Example K '■ · .... "" .- .: ^; . "

Example 4 is repeated, the _; However, no titanium oxide is added to the ABS polymer containing öt-methylstyrene. After copper-plating, the result is an adhesive strength of 1: 10 kp / inch.

Example 5- - '-' ■ ·, '- ■■ - -'- ^,'

The following mixture is produced on a mixing roller mill at a temperature of 160 ^{° C.:}

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100 parts by weight of an ABS graft polymer consisting of 27.5 percent by weight of a butadiene-styrene copolymer (90:10), 50.4 percent by weight styrene and 22.1 percent by weight acrylonitrile; 4 parts by weight of titanium dioxide ^ with a particle size distribution of 0.1 to 1, 0 / u. '- ^:

The homogeneous rolled sheet is granulated and from the 'granulate' ProTa plates with a wall thickness of 4 mm. Produced. The roughening

■ - ".- ■■ -" ■ - ■ -. ' - .. "" ■ "-". - - «'. the sample is made according to the following pickling recipe t 550 cm ^

H ₂ SO ₄ conc. dl20 °) = 1.85 g / cm ⁵ _f v-17Ö ^: "cm ³ H ₅ PO ₄ conc * d (20 °) = i

1.70 g / cm ⁹ , desalinated water 270 cm, chromium trioxide 15 g. SensiTDilization, activation and chemical and galvanic copper plating are carried out as in Example 1. The 40 yu thick copper layer of the test panels treated in this way has an adhesive strength of 5.30 kp / zoil.

Comparative example E.

If one repeats example 5 in such a way that one follows the above- '■ " mentioned ABS polymer no! titanium oxide adds, so show the Prober made from the pure ABS graft polymer body has an adhesive strength of 3.60 kp / inch after the same further treatment. '-Ζ.;.' ;

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Claims (1)

162107? Patent claim Process for the production of metal coatings on thermoplastics by treating the plastic with a pickling agent and applying an electrically conductive layer with subsequent galvanic deposition of a metal coating, characterized in that a styrene-containing plastic is used which contains 0.1 to 30 percent by weight of a solid, finely divided inorganic substance with a particle size of 0.1 to 2 yu in homogeneous distribution. " 109817/152 La A 10 672 -10-