Beta-naphthol ether sulfonates, processes for preparing them and use thereof as brightness improvers

Abstract

The present invention relates to beta-naphthol ether sulfonic acids or salts thereof having the general formula (I) RO-(AO).sub.nCH.sub.2CH.sub.2S(O).sub.3M (I), where R, AO, n and M have the definitions stated in the claims and in the description, to mixtures thereof, to aqueous solutions and to electrolytes comprising them, to processes for preparing them and to the use of these.

Claims

1. A beta-naphthol ether sulfonic acid or salt thereof having the formula (I)
RO-(AO)nCH.sub.2CH.sub.2S(O).sub.3M(I), where R is a naphth-2-yl radical which is unsubstituted or substituted by one or more radicals R.sup.1; R.sup.1 is C.sub.1-4 alkyl; n is an integer from 3 to 25; each AO independently of any other is selected from the group consisting of CH.sub.2CH.sub.2O, CH(CH.sub.3)CH.sub.2O and CH.sub.2CH(CH.sub.3)O, and M is H, Li, Na, K, Mg, Ca, Sr, Ba or N(R.sup.2).sub.4, where each R.sup.2 independently of any other is H, C.sub.1-4 alkyl, phenyl or benzyl.

2. The sulfonic acid or salt thereof according to claim 1, wherein R is an unsubstituted naphth-2-yl radical.

3. The sulfonic acid or salt thereof according to claim 1, wherein n is an integer from 6 to 20.

4. The sulfonic acid or salt thereof according to claim 1, wherein n is the sum of k+l, where k is the number of CH.sub.2CH.sub.2O groups and l is the number of both groups CH(CH.sub.3)CH.sub.2O and CH.sub.2CH(CH.sub.3)O, and where k>0 and l>0.

5. The sulfonic acid or salt thereof according to claim 4, wherein k>1.

6. The sulfonic acid or salt thereof according to claim 1, wherein AO is exclusively CH.sub.2CH.sub.2O.

7. The sulfonic acid or salt thereof according to claim 1, wherein M is Na or K.

8. A salt of a sulfonic acid according to claim 1, of the formula: ##STR00007## where n=11.

9. A mixture of a plurality of sulfonic acids or salts thereof according to claim 1.

10. The mixture according to claim 9, the sulfonic acids or salts thereof differing only in the number n of AO groups.

11. An aqueous solution comprising a salt of the sulfonic acid according to claim 1, or a mixture of salts thereof.

12. An electrolyte, comprising (A) a sulfonic acid salt according to claim 1, (B) at least one metal salt, and (C) optionally at least one metal deposition component other than (A) and (B).

13. A process for preparing a sulfonic acid or salt thereof according to claim 1, comprising: (a) reacting a compound of the formula RO-(AO).sub.n+1H with phosgene to give a compound RO-(AO).sub.nCH.sub.2CH.sub.2Cl, and (b) reacting the compound RO-(AO).sub.nCH.sub.2CH.sub.2Cl with MHSO.sub.3 to give a compound of the formula (I).

14. A method of using a salt of sulfonic acid according to claim 1, or a mixture of salts thereof in electrochemical deposition of metal.

15. A method of using a salt of sulfonic acid according to claim 1 or a mixture of salts thereof as a brightness improver.

Description

EXAMPLES

(1) 1) Reaction of Beta-Naphthol Ethoxylate (12 EO Units) with Phosgene to Give the Corresponding Chloride

(2) ##STR00003##
Experimental Description, Batch:

(3) A stirred apparatus with baffles, reflux condenser with dry-ice cooling, brine cooler, thermometer, gas introduction tube, inert gas blanketing and heated dropping funnel is charged with 0.93 g of a commercially available phosphine oxide catalyst (mixture of 4 trialkylphosphine oxides, namely R.sub.3PO, R.sub.2RPO, RR.sub.2PO, R.sub.3PO (R=n-octyl, R=n-hexyl) and the stirrer is switched on. The brine cooler is set to 30 C. and the reflux condenser is charged with acetone and dry ice, and the reactor is heated to 140 C. When the reaction temperature has been reached, 25 g of phosgene are metered in and a reflux of phosgene was observed. The metered introduction of a mixture of in total 3417.5 g of beta-naphthol ethoxylate (12 EO) and 4.57 g of the aforementioned phosphine oxide catalyst was commenced. Evolution of gas is apparent. The reactants were metered in at a rate such that there was always phosgene reflux and gas evolution observable. The temperature remains at a constant 140 C. When all of the beta-naphthol ethoxylate had been added, reaction was continued at 140 C. for 1 h, followed by stripping to a phosgene-free state at 70 C. for 22 h.

(4) Analyses carried out were .sup.1H and .sup.13C NMR, HPLC, OH number, and determination of phosphorus. All of the analyses show complete conversion to the chloride.

(5) Experimental Description, Continuous:

(6) The synthesis unit consists of a reactor cascade of 21 L miniplant reactors made from glass, with impeller stirrer and baffles, which run continuously into one another via membrane pumps with level control (to 400 ml). Desalinated beta-naphthol ethoxylate (12 EO) and the aforementioned phosphine oxide catalyst were mixed beforehand and metered into the main reactor from a heated reservoir by means of an internally heated membrane pump. Monitoring was accomplished using a balance. The reactors were initially each equipped with a 30/78 C. condenser pair. Adjoining this was a continuous facility for dephosgenation by stripping with nitrogen (about 150 L/h) in a heated bubble tray column (70 C.). The phosgene expelled in this facility was condensed and returned to the main reactor.

(7) The plant was operated with 130 g/h of a mixture of beta-naphthol ethoxylate (12 EO) and the aforementioned phosphine oxide catalyst at 0.3 mol % and 13 g/h of phosgene over a total of 30 h. After this reaction time, the plant was at equilibrium; samples were taken from the two reactors and the stripping column at regular intervals, approximately every 6 h. Analyses carried out were .sup.1H and .sup.13C NMR and HPLC, and additionally OH number and phosphorus for selected samples.

(8) 2a) Reaction of the Chloride with Na Sulfite to Give the Corresponding Sodium Beta-Naphthol Polyethoxy(11)Sulfonate (Compound 1)

(9) ##STR00004##

(10) The above-prepared chloride (1 mol) is admixed with 40% strength sodium hydrogensulfite solution (1.1 mol), and sodium beta-naphthol polyethoxy(11)sulfonate (2 wt % as aqueous solution) and potassium iodide (0.05 mol) are added. The reaction solution is adjusted to a pH of 8.5 using aqueous 10% strength NaOH solution, and then degassed with argon for 2 h with stirring. The two-phase reaction solution is transferred to a steel enamel autoclave or Hastelloy autoclave, heated to 140 C. over the course of 3 h, and maintained at that temperature for 10 h. It is then cooled, to give a homogeneous, clear and brownish reaction effluent. The pH of the product is 5.5 to 6.5.

(11) Analyses carried out were .sup.1H and .sup.13C NMR and OH number. Complete conversion of the chloride is found, to 18% beta-naphthol ethoxylate (12 EO) and 82% sodium beta-naphthol polyethoxy(11)sulfonate.

(12) 2b) Reaction of the Chloride with Na Sulfite to Give the Corresponding Sodium Beta-Naphthol Polyethoxy(11)Sulfonate (Compound 2)

(13) ##STR00005##

(14) The above-prepared chloride (1 mol) is admixed with 40% strength sodium hydrogensulfite solution (1.1 mol), and sodium beta-naphthol polyethoxy(11)sulfonate (2 wt %) are added. The reaction solution is adjusted to a pH of 8.5 using aqueous 10% strength NaOH solution, and then degassed with argon for 2 h with stirring. The two-phase reaction solution is transferred to a steel enamel autoclave or Hastelloy autoclave, heated to 140 C. over the course of 3 h, and maintained at that temperature for 15 h. It is then cooled, to give a homogeneous, clear and brownish reaction effluent. The pH of the product is 6.3.

(15) Analyses carried out were .sup.1H and .sup.13C NMR and OH number. Complete conversion of the chloride is found, to 22% beta-naphthol ethoxylate (12 EO) and 78% sodium beta-naphthol polyethoxy(11)sulfonate.

(16) Comparative Experiments:

(17) C1: beta-naphthol-(PO).sub.2.5(EO).sub.14(CH.sub.2).sub.3SO.sub.3K (comparative compound 1) in analogy to example 6 from EP 0 298 296 A1

(18) V2: beta-naphthol ethoxylate (12 EO units) reacted with 1,3-propane sultone (comparative compound 2) in analogy to C1, but without PO and with the corresponding amount of EO:

(19) ##STR00006##

(20) Lugalvan BNO12+1.08 eq KOH flakes (88% form)+1 eq propane sultone, aqueous solution. Amount: 100 g. Active content: about 77%, remainder: NIO. KF water determination: 6.4%
Application:
Test Method 1 (Brightness Throwing Power):

(21) On a standard basis, additives for electrochemical deposition of metal are investigated in accordance with DIN 50957 (January 1978) in the Hull cell with a defined volume of 250 ml. Here, the left-hand side of the test substrate represents the high current density range (CDR), the right-hand side the low CDR. This method is known to the skilled person and requires no further elucidation.

(22) Substrates used were steel plates with dimensions of 107 cm. These plates were subjected to alkaline degreasing, and to HCl pickling and then installed in the Hull cell. After coating, the plates were rinsed with water and dried in a stream of air.

(23) In order to investigate the effect of the new sodium beta-naphthol polyethoxy(11)sulfonate (AES), a base electrolyte was used, for which only the AES, at different concentrations, was added and comparison was carried out.

(24) All of the deposition tests below in the Hull cell were carried out at room temperature with a cell current of 1 A and a deposition time of 10 min.

(25) The base electrolyte selected was the following composition in water: 73 g/L ZnCl2 275 g/L KCl 25 g/L H3BO3 2 g/L sodium benzoate, 2 g/L naphthalenesulfonic acid condensation product, Na salt 1 g/L, C10 oxo-process alcohol+11 EO 1 g/I thiodiglycol (ethoxylated) 0.2 g/L benzalacetone

(26) Added to the base electrolyte are x g/L test substance (calculated on 100%).

Application Examples

(27) Below, the compounds of the invention were added at various concentrations to the above-described base electrolyte. For comparison, two products likewise constituting aryl ether sulfonates (AES) but having a CH.sub.2CH.sub.2CH.sub.2SO.sub.3K end group were tested.

(28) From the electrolyte described above, Zn is deposited in the Hull cell and the deposition picture of the zinc coat on the test substrate is evaluated for degree of brightness. Evaluation takes place of the extent of the regions on the plate that exhibits sufficient brightness, semi-brightness or a matt surface. The plate length overall is 10 cm.

(29) 3 different concentrations were measured: AES 1 g/l=underdosing AES 3 g/l=target concentration AES 10 g/l=overdosing
Amount used in electrolyte 3 g/l active substance (=target concentration)
Compilation of Data:
Gloss Regions at Target Concentration (3 g/l) were Measured from the Left-Hand Edge of the Plate

(30) TABLE-US-00001 Comparative Comparative Compound 1 Compound 2 compound 1 compound 2 Matt region 0-1.0 cm 0-1.5 cm 0-2.5 cm 0-2 cm Semi-bright 1.0-3.5 cm 1.5-2 cm 2.5-4.5 cm 2-4.5 cm Bright 3.5-10 cm 2-10 cm 4.5-10 cm 4.5-10 cm

(31) Surprisingly it was found that inventive compounds in comparison to the comparative compounds, at the same use concentration, produce a significantly greater bright region on the test substrate.

(32) This is an advantage for the coating of products in production, since it allows parts with complex shaping to be coated more uniformly.

(33) Bright Regions at Underconcentration (1 g/l), Measured from the Left-Hand Edge of the Plate

(34) TABLE-US-00002 Comparative Compound 1 compound 1 Comparative compound 2 Matt region 0-0.8 cm 0-1.0 cm 0-1.5 cm Semi-bright 0.8-3.0 cm 1.0-4.0 cm 1.5-4.5 cm Bright 3.0-10 cm 4.0-10 cm 4.5-10 cm
Bright Regions at Overconcentration (10 g/l), Measured from the Left-Hand Edge of the Plate

(35) TABLE-US-00003 Comparative Compound 1 compound 1 Comparative compound 2 Matt region 0-2.0 cm 0-3.5 cm 0-2.0 cm Semi-bright 2.0-3.5 cm 3.5-6.0 cm 2.0-3.5 cm Bright 3.5-10 cm 6.0-10 cm 3.5-10 cm

(36) Test method 2 (determination of degree of brightness):

(37) It is also possible to determine the degree of brightness using the following instrument: Dr Lange, REFO 3, reflectometer (QM instrument No. G57, ESA/EK, type No.: LMG136, instrument No.: 1012327) at a measuring angle of 85. The degree of brightness is determined on a steel plate galvanized with the above-described additive formulations comprising beta-naphthol ether sulfonates. The measurement was carried out according to the operating instructions of the REFO 3 instrument, starting at a distance in each case of 1 cm, 5 cm and 9 cm from the edge, and in the high current density range (hi range; see DIN 50957, January 1987). The degree of brightness found is the average value from 10 measurements. The standard deviation is 2 degrees of brightness. The higher the degree of brightness, the greater the brightness.

(38) TABLE-US-00004 Comparative Comparative Specimen Compound 1 compound 1 compound 2 Degree of Measurement Measurement Measurement brightness [85] point from point from point from left-hand edge left-hand edge left-hand edge in in the hI range: in the hI range: the hI range: 1 cm/5 cm/ 1 cm/5 cm/9 cm 1 cm/5 cm/9 cm 9 cm Zn on steel plate, 95/145/116 75/142/111 87/144/121 1 g/l Zn on steel plate, 85/142/118 33/110/114 51/138/115 3 g/l Zn on steel plate, 26/121/120 16/64/109 17/112/116 10 g/l Zn on steel plate, 45/52/57 45/52/57 45/52/57 basic electrolyte without additives

(39) It is clear that the degree of brightness at 1 cm and 5 cm is better for the inventive compound at all concentrations employed. At 9 cm, the surface becomes matt for all of the products tested, and the degree of brightness goes down and is similar for all products.