DE2460247A1 - PRIME GLOSS ADDITIVE FOR ACID NICKEL GALVANIZED TUBES - Google Patents

Description

Patent attorney

In «\ r ./-.- i * ^ i '. A * ~ ^; t7

Dn. DieterRiviOrf -. ■

r \, »h«! - ^ - \ η, - ..,:, «« December 19, 1974

Df. HahS-M-. fcftaiiilS. IC-6146/6146-A

8 fviünchan Ba ^ Fiänzt-nauereär »SÄ

E. I. DU PONT DE NEMORS AND COMPANY

lOth and Market Streets, Wilmington, Delaware I9898, V.St.A.

Primary brightener additive for acidic nickel plating baths

The present invention relates to the electrodeposition of bright, planar nickel from aqueous nickel salt solutions, particularly bath additives useful as primary brighteners for improving the performance of such nickel plating solutions, as well as baths and processes using such additives. _v

The state of the art in the field of nickel electroplating from aqueous nickel salt solutions is extensive and. well documented. From these baths, such as the chloride, sulfamate, Pluorborate and the well-known Watts baths galvanically Deposited nickel coatings are generally dull, have a dull finish and have for one low value commercial use. TJm shiny, flat,

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Getting ductile deposits from such baths is it necessary to add various additives or brighteners. Brighteners useful in low-grade electroplating are usually divided into two general classes based on their predominant function. Classes of primary and secondary brighteners are known in the literature. Primary gloss agents are substances that are in relatively low levels Concentrations of about 0.01 to 0.2 g / l can be used and inherently a! visible shine effect may or may not evoke. In addition, there may be detrimental side effects such as brittleness the deposition, narrow, shiny electroplating area and jump electroplating at low current densities. Secondary Shine agents are substances that can be used as shine agents in combination with primary shine agents, but in higher concentrations, usually from about 1 to 20 g / l can be used. Secondary brighteners can have a certain gloss effect on their own cause; Usually, however, they only show this effect over an inadequate current density range.

With a careful selection of primary and secondary brighteners, it is possible to produce glossy, even and ductile deposits to be achieved over a wide current density range.

In modern procedures, the Watts bath is mostly used, an aqueous solution of nickel sulfate, nickel chloride and boric acid, combined with a suitable additive system Is used. The additive system usually contains highly polar or unsaturated compounds as the primary gloss agent, such as pyridinium salts or acetylenic alcohols and various organic sulfonic acid, Sulfonamide and sulfonimide compounds as disclosed in U.S. Patents 2,191,813 and 2,466,677 are disclosed. Among the more preferred secondary gloss agents are saccharin and its sodium or potassium salt, sodium allyl sulfonate, naphthalene and tri-sulfonic acids, dibenzenesulfonimide and sodium 3-chlorobutene-i-sulfonate. Often there are mixtures of these secondary ones

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Gloss agent used. Acetylenic alcohols and their derivatives are now generally preferred as primary brighteners, because they have less tendency to form brittle deposits and control their concentration in that Bad is less critical. One of the most preferred brighteners is because of its performance, availability and low Cost of 2-butynediol- (1,4), which is disclosed in U.S. Patent 2,712,522 is discussed.

The use of 2-btrtin-diol- (1,4) in connection with secondary Brighteners of the type described above in the Vatts bath give pearly glossy, even deposits with good results Ductility; however, there is a tendency to form deposits with holes and dark, thin coatings and to the occurrence of crack or empty plating low current densities. To minimize these problems to restrict become common. Derivatives of 2-butyne-diol- (1,4) are used. Among the more favorable are hydroxyalkyl derivatives, which one by the base-catalyzed addition in the of various epoxides to 2-butyne-diol- (1,4), as it disclosed in U.S. Patent 3,366,557. An addition of reduced more than about 2 or 3 moles of epoxide per mole of butynediol Although the problems that occur at low current density, it also easily leads to undesirable losses in gloss formation and equalizing ability. Similarly, acetylenic alcohols are of higher molecular weight than Butynediol, while useful, are generally less effective. U.S. Patent 3,699,016 discloses symmetrical hydroxyalkine sulfonates disclosed, which is obtained by the acid-catalyzed reaction of acetylenic diols with epihalohydrins and subsequent conversion of the halide group into a sulfonate group by reaction with sodium sulfite. In conjunction with aromatic sulfur compounds as secondary brighteners, these compounds give a good mode of action overall, some of them seem to have a certain tendency to form a white veil high current densities.

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The present invention relates to an aqueous solution of a mixture of alkyne compounds of the general formula

in which:

R ¹ fi -0-CH-CH ₀ - or -0-CH ₀ -CH-

i ^{2 2} I.

CH ₀ SO _x M CH ₀ SO, M

-0-CH-CH ₀ - or -0-CH ₀ -CH-I ^{2 2} |

CH, CH,

5 p

R- '-CH-CH ₂ -O- or -CH ₂ -CH-O-.

nil ΓΉ

3 3

χ, m and η integers, namely

x «0 or 1; m + η «0, 1 or 1; χ + m + η = 0, 1 or 2 and

M hydrogen or a metal, namely sodium, potassium or nickel.

Provide at least 50 mol% of the mixture of alkyne compounds

v.

asymmetric alkynesulfonic acid compounds and less than 50 Mo 1% of the mixture represent other alkyne compounds. The concentration of the alkyne compounds in the mixture is in the range from about 0.01 mmol per liter to saturation. About 0.1 to 2 moles per liter of the alkyne compounds are desirable concentrations for a primary gloss additive. About 0.1 to 10.0 millimoles per liter is desirable in an electroplating bath, and about 1 to 2 millimoles per liter

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are optimal. The concentration of the alkyne compounds can be "easily determined from that used in the preparation of the compounds Determine the amount of butynediol.

The additives are largely asymmetrical in nature; They are made by first adding about 0.5 to 1.5 mol propylene oxide with boron trifluoride catalysis to 1 hol 2-butynediol- (1,4) and then about 1 to 2 moles of epichlorohydrin admits in such a way that the sum of the moles of propylene oxide plus the moles of epichlorohydrin, which per mole of 2-butynediol- (i, 4) have been added is between about 2.0 and 30, and preferably about 2.5. The brown, viscous, Water-insoluble products are made soluble by reaction with aqueous sodium sulphite and in the process in mixtures converted by compounds which are the additives according to the invention.

Because of the method of preparation, one can obtain mixtures comprising a variety of combinations of acetylenic compounds contain. The important alkyne compounds within the mixture can, however, by the general ones given above Formula to be described. In addition, those compounds which make up the main molar fraction (at least Make up 50 mol? Q of the mixture of alkyne compounds, as the following three asymmetric alkynesulfonic acids are identified:

1. 1-Hydroxypropoxy-4-sulfohydroxypropoxy-butyne- (2)

HO-CH-CH ₀ -O-CH ₀ -ChG-CH ₀ -O-GH ₀ -CH-OH ₍ 2 2 ²² |

CH, CH ₀ SO _x H

P 2 p

2. i-hydroxy-4-sulf ohydroxypropoxy-butyn (2) HO-CH ₂ -CsC-CH ₂ -O-CH ₂ -CH-OH

d. >

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3. 1-Hydroxy-4-sulfohydroxypropoxy-propoxy-butyne- (2)

C C C \ C

CH _x

In addition to these asymmetric alkynesulfonic acids, a smaller mole fraction (less than 50 mol%) is composed of the following alkynols:

4. 1,4-Dihydroxy-butyn (2) HO-CH ₂ -C = C-CH ₂ -OH

5- 1-hydroxy-4-hydroxypropoxy-butyn (2) HO-CH ₂ -CHC-CH ₂ -O-CH ₂ -CH-OH

CH _x 7

6. 1,4-Di (hydroxypropoxy) butyne- (2) HO-CH-CH ₀ -O-CH ₀ -C = C-CH ₀ -O-CH ₀ -CH-Oh

IC. C. C. C.

CH, CH,

The structures given for compounds 1 to 6 are those of certain isomers; it is understood that the other isomers of the propoxy and sulfohydroxypropoxy groups are also intended to be included in acid catalyzed reactions. In Kirk-Othmer "Encyclopedia of Chemical Technology", 2nd Edition, Volume 16, pages 598, when discussing this subject, it is stated that when an epoxide such as propylene oxide is added to an alcohol of the ROH type under acid catalysis conditions, the adduct obtained is a mixture of a primary alcohol, R-O-CH-CH ₂ »OH

CH _x and a secondary alcohol, RO-CH ₂ -CH · 0Η, roughly

_{Contains 5} equal amounts. In contrast, according to

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Kirk Othmer when the reaction is catalyzed by base is almost exclusively the secondary alcohol.

In the inventive application of acid catalysis, therefore with the term "hydroxypropoxy" both groups:

-0-CH-CH ₀ -OH and -0-CH ₀ -CHOH I ^{2 2} I.

CH-, CH _x

and with the term "sulfohydroxypropoxy" both groups:

-0-CH-CH ₂ -OH and -0-CH ₂ -CHOH CH ₂ SO ₅ H 'CH ₂ SO ₅ H

described. Similarly, 1-hydroxy-4-hydroxypropoxypropoxy-butyne- (2) equivalent to 1,4-Li (hydroxypropoxy) butyne- (2).

A particularly desirable mixture of additives contains a mixture of alkyne compounds which, in mol%, contain about 5 to 50% of each of the asymmetric alkynesulfonic acids 1-hydroxypropoxy-4-sulfohydroxypropoxy-butyne- (2), 1-hydroxy-4-sulfohydroxypropoxy-butyne- (2) and i-hydroxy-4-sulfohydroxypropoxypropoxy-butyne- (2) and about Λ to 35 % of each of the alkyne compounds Λ , 4-dihydroxy-butyne- (2), 1-hydroxy-4-hydroxypropoxy-butyne- ( 2) and 1,4-di (hydroxypropoxy) butyne- (2).

The invention also includes electroplating baths containing additives which exhibit the above-discussed active ingredients plating using such baths at current densities in the range of Λ to 15ΟΟ A / m and preferably from 10 to 1000 A / _m ² (0.1 to 15Ο A ./ft. ² ) preferably 1 to 100 A./ft. ) as well as methods of manufacture

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such active ingredients.

The present invention relates to nickel electroplating from the person skilled in the art of aqueous, acidic nickel. galvanizing baths. These baths are made by dissolving at least of a nickel salt in aqueous, acidic solution. A recent publication which gives an excellent overview of the technique of galvanic production of shiny, even nickel coatings "Nickel and Chromium Plating" by J. K. Dennis and T. E. Such (this Halsted Press book was written by John Wiley and Sons, Released in 1972). The operating conditions disclosed in this book, for example pH, temperature, current density and concentration of the bath components are dependent on the present Invention applicable to use in the various types of metal plating baths. Generally lies the pH in the range of 3 to 5 and usually from 4 to 4.5, while the temperature is in the range of 40 to 70 ° C and usually 55 to 65 ° C.

Practically all baths for galvanizing bright nickel contain nickel sulfate, a chloride, to a large extent Nickel chloride, a buffering agent, usually boric acid, and optionally a wetting agent. Such baths include the well-known Watts bath and the high chloride bath. Other baths can contain other nickel salts as a source of nickel, such as nickel sulfamate, nickel fluoroborate or mixtures these salts with nickel sulfate or nickel chloride. Typical Vatts and high chloride baths are: The following:

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Watts High chloride content

NiSO ₄ -7H ₂ O g / l. 200-400 40-150

NiCl _{2 -6H 2} O, g / l 30-80 150-300

Boric acid, g / l 30-50 30-50

Temperature, ⁰ C 55-65 55-65

pH 3-5.3-5

In practicing the present invention the bath additives are used in conventional nickel electroplating beer baths, such as the Watts baths and high chloride baths described above, in amounts equal to 0.1 mmole to 10 mmol of total alkynes per liter of electroplating bath, the optimal concentrations being 0.5 to 2 mmol per liter are used. The alkine additives themselves are taken together in the additive solutions expediently in concentrations of 0.1 to 2 mol / l although other concentrations can be used. To achieve maximum gloss, maximum leveling effect and suppleness is the use of a secondary gloss agent or mixtures of secondary gloss agents, as described above, in amounts of 1 to 20 g / l required. From a practical point of view The most useful of the secondary brighteners are saccharin and the in terms of cost and effects Naphthalene-di- and tri-sulfonic acids. Except for these aromatic ones Sulfur compounds can include other sulfur compounds, often referred to as "secondary auxiliary brighteners", such as sodium allyl sulfonate or sodium 3-chloro-butene (2) -1-sulfonate, be present in amounts of 1 to 10 g / l. Finally, it is often desirable that in the bathroom as well a small amount of a wetting agent, such as sodium ethylhexyl sulfonate, is present so that the quality of the coating is further improved and the problems of pitting corrosion, caused by gas bubbles trapped on the cathode surface must be kept to a minimum.

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AO

The invention can be understood in more detail on the basis of the following examples.

example 1

0.25 mol of 2-butyne-diol- (1,4) was placed in a 500 ml round bottom flask equipped with a heating mantle, stirrer, thermometer and dropping funnel and poured into a 500 ml. (1,4), which is 54 ° C. 1 ml of boron trifluoride etherate was added to the molten 2-butynediol- (1.4), the heating mantle was then removed, and 0.288 mol of propylene oxide was added dropwise, the contents of the flask under autogenous pressure and the temperature by means of the exothermic heat of reaction between 50 and kept at 60 ° C. Upon completion of the propylene oxide added 0.338 mole of epichlorohydrin were added while maintaining autogenous pressure and temperature were maintained between 40 and 45 ⁰ C. After the addition of epichlorohydrin was complete, stirring was continued for 1 hour while the reaction mixture cooled to room temperature. The brown, viscous, water-insoluble butynediol / propylene oxide / epichlorohydrin condensation product was then solubilized by refluxing it with 0.338 moles of lithium sulfite in aqueous solution; an aqueous additive was formed which had a concentration of about 0.25 mol / l of alkyne compounds per liter of the mixture.

About the composition of the mixture of alkyne compounds thus prepared To define more precisely, five butynediol / propylene oxide / epichlorohydrin condensation products were prepared as indicated above separated into their components by gas chromatography before the reaction with aqueous liatrium sulfite, and the individual components were mass spectrographed further studied the molecular weight and the number of chlorine atoms contained in the compounds of the ingredient to determine. It has been found that the main ingredient in

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AK

the condensates contained 1 chlorine atom per molecule and had a molecular weight of 236 mass units, which is one Compound corresponds to 1 mole of butynediol / 1 mole of propylene oxide / 1 Contains moles of epichlorohydrin. When reacted with aqueous sodium sulfite, this compound gives 1-hydroxy-4-sulfohydroxypropoxy-butyne- (2) and its isomers. To other alkyne compounds in the condensates, which by means of The mass number identified and contained chlorine belong to a compound containing 1 mole of butynediol / 1 mole of epichlorohydrin and contains small amounts of unreacted butynediol, and butynediol, the one with 1 and 2 moles of propylene oxide is condensed. Found in only one of the five condensate samples a lesser amount of a compound with a mass weight of over 236 mass units. This connection was' detected after a lengthy elution from the gas chromatography column. This connection agrees with a butynediol which is condensed with 2 moles of epichlorohydrin; but it may be that they are atypical for the reaction product is because it was only found in one out of five similar samples.

Secondary alcohols resulting from the addition of propylene oxide of butynediol and contained in smaller amounts in the mixture of alkyne compounds according to the invention are 1-hydroxy-4- (2'-hydroxypropoxy) -butyne- (2) and 1,4-di (2'-hydroxypropoxy) butyne- (2); these connections are disclosed in the aforementioned U.S. Patent 3,366,557. the Use of mixtures of butynediol and butynediol / propylene oxide condensates in the case of Mckelgalvanisierung is in the U.S. Patents 3,711,384 and 3,804,727; Similar disclosures can be found in DT-OS 2 224 783. The total amounts on these alkynol compounds which are used in the preferred embodiments of the present invention, are, however, much less than the state of the art considered necessary; this increases the effectiveness of the asymmetric alkynesulfonic acids, which, the major mole fraction make up according to the present invention, illustrated.

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AX

The use of certain other alkynesulfonic acids is disclosed in U.S. Patents 2,800,442 and 2,841,602. In the latter In the patent specification, the acids disclosed are limited to those which have an unsubstituted alkane group having 1 to 4 carbon atoms, while U.S. Patent 2,800,442 limits the acids disclosed to those which have an aromatic aryl group.

Eg game 2

The procedure of Example 1 was followed with the modification that 0.376 moles of propylene oxide with 0.25 moles of 2-butynediol- (1.4) and subsequently reacted further with 0.25 mol of epichlorohydrin. The product thus formed was made by reaction Solubilized with aqueous sodium sulfite, and again an aqueous additive was prepared which had a concentration of about 0.25 mol / l of the mixture of alkyne compounds in water.

Example 3

A Watts bath that

• 7H ₂ 0 300 g / l

• 6H ₂ 0 60-g / l

H ₅ BO ₅ 40 g / l

pH 4.5

contained were added:

The composition of matter according to

Example 1 x 1.0 mmol / 1

Saccharin 2.0 g / l

Sodium ethylhexyl sulfate 0.04 g / l

With this bath, an electroplating test was carried out at 55 "to 60 C in a 267 ml Hull cell using a measuring

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Al

single cathode, with a Meclianis stirrer, whose stirring blade moved parallel to the cathode face, was stirred. It was at 2 amps for 10 minutes galvanized. Before electroplating, the plate was cleaned lengthways with an emery cloth (sanding sand No. 600; 600-grit) sanded in one pass to allow a visual comparison of the leveling, and then cathodically in a commercial, aqueous, alkaline Brass cleaning bath cleaned. The test carried out as described in the. Hull cell revealed over the entire frontal area the plate has a very shiny nickel coating. The Ega

Iizing effect above 120 A / m was very good, i.e. H. the most of the scratches were covered. An even top coat of semi-glossy nickel was also applied over the back of the Plate deposited, which further proves the good functioning of this bath at low current density.

Example 4

A high chloride bath that

NiSO ₄ -

50 g / l 200 s / i 40 6/1 4.5 • 1.0 mmol / 1 4.0 g / l

contained were added:

The agent according to example 2 saccharin

A test carried out with this bath using the Hull cell according to the electroplating method described in Example 3 again gave a high gloss nickel coating over the entire surface of the plate. The equalizing effect

ρ.

above 120 A / m was good, ie the visibility of the scratches was considerably reduced. A uniform coating of semi-bright nickel was also deposited over the back of the plate, which works well at low current.

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JH

density proves.

Example 5

3 liters of a bath were made that

₄ -7 H ₂ O 300 g / l

NiCl ₂ -6H ₂ O 60 g / l

H ₅ BO ₅ 40 g / l

Saccharin 2 g / l

pH 4.5

contained, and heated to 55 to 60 ° C. A series of bent cathode plating tests using increasing amounts of the additive of Example 1 were then carried out. The curved cathodes consisted of 4.13 cm χ 12.7 cm (1-5 / 8 in. Χ 5 in.) Large steel plates with a wide "V" at an angle of approximately 45 ° »the sides (2.54 cm) were each bent in the middle. The electroplating was carried out at 5 amps for 30 minutes at an average current density of 450 A / m. Before the bending, the cathodes were scratched open on both sides with emery cloth (sanding sand No. 240) in one pass in order to make a comparison of the subsequent leveling visible. Only one anode was used. It faced the open side of the V of the cathode. Vigorous agitation was achieved by means of an air bubble generating device located below the cathode. The results obtained are summarized in Table II. ^v

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Table II

Trial - Amount added No. of additive

according to example 1 mmol / 1

0.33 results

0.66

2.0

4.0 Generally shiny nickel. Good coverage everywhere; to the Edges a bit dull, however. Good equalization both on the front and the back.

Pearlescent nickel everywhere. Very good to excellent leveling on the front side. Very good equalization on the back.

Pearlescent nickel everywhere. Excellent equalization on ~ the front. Very good equalization on the back.

Pearlescent nickel everywhere. Excellent equalization on the front and the back.

Similar to experiment 4 ·.

Good leveling - the scratches are considerable

covered but still visible

Very good leveling - the scratches are mostly covered; some scratches are however visible

Excellent leveling - only a few scratches are visible.

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Claims (1)

Claim Primary luster additive for acidic Mckel plating baths, containing an aqueous solution of a mixture of alkyne compounds, characterized in that the alkyne compounds the formula: in which mean: R ¹ -0-CH-CH ₀ - or -0-CH ₀ -CH- I ^{2 2} I. CH ₀ SO _x M CH ₀ SO, M -0-CH-CH ₂ - or -0-CH ₂ -CH- 'CH ₂ CH, ■ 2? -CH-CH ₂ -O- or -CH ₂ -CH-O- CH, CH, x, m and η are integers such that x = 0 or 1, m + η «0, 1 or 2 x + m + n = 0, 1 or 2; and M is hydrogen or a metal, namely sodium, potassium or Mckel, and that at least 50 mol% of the mixture of alkali compounds asymmetric alkynesulfonic acid compounds and less than 50 Mo 1% of the mixture are other alkyne compounds. - 16 509828/0810