WO2002055568A2

WO2002055568A2 - Use of polyolefins with alkaline, aromatic substituents as auxiliaries in the electrolytic deposition of metal layers

Info

Publication number: WO2002055568A2
Application number: PCT/EP2001/014675
Authority: WO
Inventors: Ferdinand Leifeld; Rainer Urich; Isolde Ortmann
Original assignee: Raschig Gmbh
Priority date: 2001-01-11
Filing date: 2001-12-13
Publication date: 2002-07-18
Also published as: EP1373336A2; WO2002055568A3; DE10100954A1

Abstract

The invention relates to the use of polyolefins with alkaline, aromatic substituents of the general formula (I), wherein Ar is an alkaline aryl group or a phenyl, an alkyl having 1 to 8 carbon atoms or hydrogen, with at least 50 % of the groups representing an alkaline aryl group and n being an integer of from 2 to 3000, as additive in electrolytic baths. The invention further relates to electrolytic baths containing said polyolefins and to a method for electrolytically depositing metal layers.

Description

Use of polyolefms with basic, aromatic substituents as an aid for the electrolytic deposition of metallic layers.

The present invention relates to the use of polyolefins with basic, aromatic substituents as auxiliaries for the electrolytic deposition of metallic layers. The product can be used in acidic, galvanic copper baths as well as in alkaline zinc baths or in alkaline zinc alloy baths. The copper baths can be used for decorative deposition, for example for automotive parts and for reinforcing conductor tracks in printed circuits. The alkaline zinc baths serve mainly as protection against corrosion.

It has been known for a long time that in the deposition of metallic layers from galvanic baths, the properties of the deposition, for example gloss, scatter and corrosion resistance, can be improved by the addition of organic auxiliaries.

US Pat. No. 3,328,273 (1967) describes the deposition of copper from an acidic, galvanic bath in the presence of SPS, polypropylene glycol and the Janus green dye. DE-OS 2541 897 describes a combination of SPS, ethoxylated or propoxylated polyethyleneimines, which were then reacted with the benzyl chloride. US-P 4,036,711 proposes the use of quaternized alkyl and aryl amines together with sulphoalkyl sulfides and polyethylene glycols. DE-PS 20 39 831 the use of polymeric phenazonium compounds is presented. To improve scattering and metal distribution, DE 19643 091 A1 describes the use of water-soluble polyamides crosslinked with epichlorohydrin. Galvanizing from alkaline, cyanidic zinc baths has been known for many years. Due to disposal problems and toxicity of cyanides, this type of bath is increasingly being replaced by alkaline, non-cyanide baths. US Pat. No. 4,135,992 (1979) describes an alkaline, cyanide-free zinc bath in which alkylated polyimines in combination with aldehydes, benzyl-3-sodium-carboxy-pyridinium chloride (BN-betaine) or imidazole derivatives lead to a shiny zinc layer. DE 35 38 147 C2 (1985) presents a reaction product of imidazole, morpholine and epichlorohydrin, which is said to reduce the tendency to form bubbles in alkaline zinc bath. US Pat. No. 5,435,898 (1995) describes the use of cationic polymers with urea structures for alkaline zinc and zinc alloy baths.

The galvanic baths described often lead to unsatisfactory results in terms of gloss, leveling and metal distribution as well as problems with the layer properties, such as corrosion protection and ductility.

Acidic copper baths can deposit layers with good gloss and scattering, but they have problems with leveling. A particular disadvantage is the lack of leveling in low current densities.

With alkaline, non-cyanide zinc baths and zinc alloy baths it is possible to deposit metal layers with a satisfactory gloss, but they do not have a uniform metal distribution in high and low current densities. It is also problematic that many of the formulations mentioned in the literature deposit zinc layers, which lead to flaking and blistering.

The problems could be solved directly by using polyvinylpyridine in acidic, galvanic copper baths and alkaline, galvanic zinc baths as well as alkaline zinc alloy baths. So far, polyvinylpyridines have been used in a wide variety of applications.

DE-OS 3040 047 (1981) and DE-OS 27 01 144 (1977) explain the application in the fields of lithography and reprography. US Pat. No. 2,874,047 and US Pat. No. 3,459,580 describe the use of polyvinylpyridines or their quaternary salts as coating material for the protection of photographs.

The dyeability of nylon fibers or polyester fibers can be improved by incorporating polyvinylpyridines (SU-P 3,361,843 (1963)).

Films filled with chromium made of polyvinylpyridine improve the corrosion protection of galvanized steel sheets (EP 0 770 712 from 1997). Microparticles of palladium, platinum or iridium in coatings made of polyvinylpyridines on pH measuring electrodes improve their stability. (Anal. Chem. (1990), 62 (2), 151-7)

In electrochemistry, polyvinylpyridines are used especially for the production of electrically conductive coatings. In WO 9404591 (1994) electrically conductive coatings from e.g. Polyvinylpyrrolidone or poly (2-vinylpyridine) are described, which make it possible to make non-conductive plastics conductive by coating and thus to make them metallizable.

Surprisingly, it was found that the use of polymeric 2-vinylpyridine and / or 4-vinylpyridine or their copolymers in acidic, galvanic copper baths a significant improvement in leveling down to low current densities and in alkaline, galvanic zinc baths and zinc alloy baths an improvement in gloss and Effect metal distribution. In addition to the electrodes, the usual inorganic and organic constituents, the galvanic baths described here also contain an additive formed from the polymerization of 2-vinylpyridine or 4-vinylpyridine.

Since it is important according to the invention to align the basic pyridine groups on the polyolefin skeleton, it is assumed that corresponding polyolefins with quinoline or pyrazine side groups react in the same way and also copolymerization with up to 50% alkylenes with 2-10 C atoms, and possibly styrene, useful products. These products according to the following general formula

in which Ar represents a basic aryl radical such as 2- or 4-pyridyl, 2-quinolyl or 2-pyrazolyl or a phenyl, an alkyl having 1 to 8 C atoms or hydrogen, at least 50% of the groups representing a basic aryl radical and n represents an integer from 2 to 3000.

Linear polyvinyl pyridine polymers can e.g. according to US Pat. No. 5,824,756 can be produced in different ways from 2-vinylpyridine or 4-vinylpyridine or copolymerization of 2-vinylpyridine and 4-vinylpyridine. The reaction can be initiated via radical initiators, by irradiation or Ziegler-Natter catalysts. The polymerizations can be carried out in bulk, emulsion or solution. Depending on the type of production, the H atoms shown in the general formula at the beginning and end of the chain can be wholly or partly e.g. be replaced by the radical starter.

The polymers used in this invention were primarily produced by radical initiators in solution or as an emulsion. Alcohols such as methanol and ethanol or else water and also mixtures thereof can be used as solvents. Sodium peroxodisulfate, for example, Dibenzoyl peroxide or azobisisobutyronitrile can be used. To carry out the reaction, 2-vinylpyridine or 4-vinylpyridine or a mixture of 2-vinylpyridine and 4-vinylpyridine is introduced into the solvent, the radical initiator is added and the mixture is stirred at 30 ° C. to 100 ° C. for 2 to 20 hours. The average molar mass of the reaction products can be in the range from 210 to 300,000 g / mol, preferably in the range from 1,000 to 100,000 g / mol.

The polymers according to the invention are obtained from the preparation as a solution or emulsion and are normally used directly without further purification.

The concentrations of the solutions achieved are typically between 5 and 30% by weight. The products obtained (based on the solid) are added to the acidic copper bath in amounts of 0.001 to 5 g / l bath. In the case of an alkaline zinc bath or zinc alloy bath, the addition amounts are in the range of 0.005 to 10 grams per liter of bath.

In addition to the polymers described, the acidic copper bath can also contain further organic additives known per se. The combination with at least one sulfur compound rendered water-soluble by sulfopropylation is advantageous. The following table shows some examples with the preferred amounts:

In addition, wetting agents, polyethers, polyamides crosslinked with epichlorohydrin and other additives customary in an acid copper bath may also be present in the bath. Beta-naphthol alkoxylates such as Ralufon NO 14 with 2.5 moles of propylene oxide and 14 moles of ethylene oxide in amounts of 0.001 to 1 g / l can be used as wetting agents, and as crosslinked polyamide EXP 2887 (epoxyimidazole polymer) in amounts of 0.001 to 0.5 g / l.

The inorganic constituents of the acid copper bath are preferably copper sulfate, sulfuric acid and chlorides, but other copper salts and other acids, such as fluoroboric acid or methanesulfonic acid, can also be used instead of sulfuric acid. The bath preferably contains between 50 and 250 g / l copper sulfate (CuSO ₄ * 5H ₂ O), between 25 and 250 g sulfuric acid and between 0.01 and 0.5 g / l chloride ions.

In addition to the polymeric vinylpyridines described, alkaline zinc baths or zinc alloy baths can also contain 0.1-50 g / l of reaction products of epichlorohydrin with amines, benzyl-3-sodium-carboxy-pyridinium chloride, polyimides and their reaction products, and also aldehydes such as anisaldehyde or vaniline the known amounts for such baths contain 0.1 - 10 g / l. The bath usually contains zinc ions as inorganic constituents in amounts of 2-20 g / l, preferably 5-20 g / l, 30-250 g / l NaOH and Na ₂ CO ₃ . Complexing agents such as gluconates or tartrates (1-50 g / l) can also be added to the baths. The alkaline zinc alloy baths can also contain nickel, iron or cobalt ions. The movement in the galvanic bath is carried out by blowing in air or by moving the cathode. A combination of both types of movement is also possible.

The following examples show the improvement of the electroplating baths by the addition according to the invention, without restricting the invention thereto.

Example 1 :

Composition of the basic bath: 210 g / l copper sulfate ^* 5H ₂ 0

75 g / l sulfuric acid 1 ml / l hydrochloric acid 10%

Organic bath additives: 0.100 g / l polyethylene glycol (Mg.Approx. 9000 g / mol)

0.020 g / l SPS 0.020 g / l DPS 0.020 g / l EXP 2887

A brass sheet coated at 25 ° C, with air movement and at 2 A in a Hull cell showed a shiny, ductile copper layer with good scattering but only slight leveling. By adding 0.02 g of an approximately 10% aqueous, acetic acid solution of a 2-vinylpyridine polymer with an average molecular weight of the polymer of approximately 70,000 g / mol, a clear leveling down to 0.4 A / dm ² can be achieved ,

Example 2:

The inorganic base bath is unchanged from example 1, the electrolyte temperature was 20 ° C. and it was galvanized at 1.5 A in the Hull cell. Organic bath additives: 0.12 g / l Ralufon NO 14

0.04 g / l OPX 0.020 g / l EXP 2887

The copper deposit is highly shiny and ductile with a very low leveling. In the bath, 0.03 grams per liter of an approximately 20% ethanolic solution of a poly-4-vinylpyridine with an average molecular weight of approximately 5000 g / l was added. The subsequent coated Hull cell sheet is highly glossy and leveled at a current density of over 0.3 A / dm ² .

Example 3

Composition of the basic bath: 12.5 g / l zinc oxide

120.0 g / l NaOH 50.0 g / l Na ₂ CO ₃

Organic bath additives

Complexing agent 1.5 g / l potassium sodium tartrate

1.0 g / l of reaction product from epichlorohydrin

Morpholine and imidazole (MOME according to DE 35 38 147) 2.0 g / l reaction product from epichlorohydrin and imidazole (IME according to DE 35 38 147) 3.0 g / l reaction product from polyimine with propanesulfone

(Leveller 135 CU) 0.1 g / l 1-benzyl-3-sodium carboxypyridinium chloride

(BN betaine 48%)

The bath was tested at 20 ° C in a Hull cell using a steel sheet as the anode. Air was blown in to move the bath. A steel sheet coated at 1 A for 10 minutes showed a zinc layer with satisfactory Shine. At three different current densities, the following were made

Layer thicknesses measured:

7 μm at 4 A / dm ² , 6 μm at 2 A / dm ² and 5 μm at 0.5 A / dm ² .

0.02 g / l of a 20% ethanolic solution of a copolymer of 2-vinylpyridine and 4-vinylpyridine (molar ratio 1: 1) is added to the bath. The polymer had an average molecular weight of approximately 2000 g / mol. A subsequently coated steel sheet showed high gloss over the entire current density range and the following metal distribution: 5 μm at 4 A / dm ² , 5 μm at 2 A / dm ² and 5 μm at 0.5 A / dm ² .

Even after tempering at 70 ° C for 24 hours, there are no bubbles and no flaking.

Claims

claims

1. Use of polyolefms with basic, aromatic substituents of the general formula:

in which Ar represents a basic aryl radical or a phenyl, an alkyl having 1 to 8 C atoms or hydrogen, where at least 50% of the groups represent a basic aryl radical and n represents an integer from 2 to 3000, as an additive in electroplating baths.

2. Use according to claim 1, characterized in that the basic aryl radical is 2-quinolyl, 2-pyrazolyl, 2-pyridyl, 4-pyridyl or mixtures of the two pyridyls.

3. Use according to claim 1 or 2, characterized in that the average molecular weight of the polyolefins is between 1000 and 100,000 g / mol.

4. Use according to one of claims 1 to 3, characterized in that the galvanic baths are acidic copper baths.

5. Use according to claim 4, characterized in that the amounts of polyolefins used in acidic copper baths of 0.001 - 5 g / l.

6. Use according to claim 3 to 5, characterized in that the polyolefins are used in combination with at least one thio compound.

7. Use according to one of claims and 3 to 6, characterized in that the thio-connection comes from the group of connections PLC, MPS, DPS, OPX, UPS and ZPS.

8. Use according to one of claims 1 to 3, characterized in that the galvanic bath is an alkaline, cyanide-free zinc bath.

9. Use according to claim 8, characterized in that the amounts of polyolefins used are in the range 0.005 to 10 g / l.

10. Use according to one of claims 1 to 3, characterized in that the bath is an alkaline zinc alloy bath.

11. Electroplating bath for the electrolytic deposition of metallic layers, characterized in that it contains polyolefins with basic aromatic substituents of the general formula

in which Ar represents a basic aryl radical or a phenyl, an alkyl having 1 to 8 carbon atoms or hydrogen, where at least 50% of the groups represent a basic aryl radical and n represents an integer from 2 to 3000.

2. Process for the electrolytic deposition of metallic layers, characterized in that polyolefins of the general formula

in which Ar represents a basic aryl radical or a phenyl, an alkyl having 1 to 8 C atoms or hydrogen, where at least 50% of the groups represent a basic aryl radical and n represents an integer from 2 to 3000, are added to the electroplating bath.