KLOUBEK JIRI (CZ)
HOUFEK JIRI (CZ)
KRIZ VACLAV (CZ)
KLOUBEK JIRI (CZ)
HOUFEK JIRI (CZ)
| US6652728B1 | 2003-11-25 | |||
| US5435898A | 1995-07-25 | |||
| US5405523A | 1995-04-11 |
C l a i m s
1. Nitrogen polymer additive for electrolytic deposition of zinc and zinc alloys of general formula I
(I)
wherein
Z means CH 2 -CH(OH)CH 2 or (C r H 2r ) -0- (C r H 2r ) or C q H 2q , wherein r = 1 to 6 and q =1 to 6, a = 0 to 1, b = 0 to 1, a + b = 1, x = 0 to 1, y = 0 to 1, x + y = 1 and n is at least 2, R, R 1 , R ' ,R ' i independently mean C m H 2 m+i wherein m = 1 to 3 or -CH 2 OH or -CH 2 CH 2 OH or -CH 2 CH(OH)CH 3 or -CH 2 CH(OH)CH 2 OH or may be identical, R 2 means (CH 2 ) c wherein c = 2 to 6,
R 3 means C=O, C=S, C=NH or O=C (CH 2 ) d C=0, wherein d =2 to 6, R ' 2 means (CH 2 J 9 , wherein g = 2 to 6 and
R ' 3 means C=O, C=S, N=NH or O=C (CH 2 ) h C=0, wherein h = 2 to 6, as a reaction product of at least one amino derivative of general formula II
(H) and at least one amino derivative of general formula III
wherein all general symbols used have the meaning stated above, with at least one halogen derivative from the group of epihalogenhydrin and/or 1, 3-dichloro-2-hydroxypropan and/or dihalogenalkane of the general formula X- (C q H 2q ) -X, wherein q=l to 6 and X means Cl, Br or I and/or dihalogenalkylether of the general formula X- (C r H 2r ) 0- (C r H 2r ) -X wherein r = 1 to
6 and
X means Cl, Br or I.
2. A process for producing a nitrogen polymer additive of claim 1, c h a r a c t e r i z e d i n t h a t 1 mol of a mixture of amino derivatives is contacted with 0,5 to 1,5 mol of a halogen derivative in an aqueous or in a suitable organic medium at a temperature of 20 0 C to the reflux temperature, preferably 90 0 C to the reflux temperature for 1 to 48 hours.
3. Use of the nitrogen polymer additive according to claim 1 for electrolytic deposition of zinc and zinc alloys wherein 0,1 to 20 g/1 of the nitrogen polymer additive is added to a zinc plating bath containing 2 to 50 g/1 of Zn, 10 to 300 g/1 of NaOH and/or KOH and/or LiOH and optionally to 100 g/1 Na 2 CO 3 .
4. The use according to claim 3, wherein complex Fe and/or Co and/or Ni and/or Mn is added to the bath in an amount of 0,01 to 50 g/1.
5. The use according to claims 3 and 4 wherein selected nitrogen oligomers or polymers are added to the bath in an amount of 0,1 to 20 g/1.
6. The use according to any of the claims 3 to 5, wherein compounds containing divalent sulphur, Na 2 S and/or thiourea and its derivatives and/or heterocyclic compounds containing the group C=S are added to the bath in an amount of 0,01 to 5 g/1.
7. The use according to any of the claims 3 to 6, wherein aromatic aldehydes and/or other aromatic compounds are added to the bath in an amount of 0,001 to 1 g/1.
8. The use according to any of the claims 3 to 7, wherein silicates, polyhydroxy acids or other compounds forming complexes are added to the bath in an amount of 0,1 to
100 g/1. |
Nitrogen polymer additive for electrolytic deposition of zinc and zinc alloys and process for producing and use of the same
Field of the invention
The invention relates to nitrogen polymer additives and a process for producing these additives as well as the use of them during electrolytic deposition of zinc and zinc alloys .
Background of the invention
For ecological and hygienical reasons the use of toxic cyanide baths that during the 80th years of the 20th century occupied more than 50% of the whole capacity of the galvanic zinc coating is gradually abandoned. In the course of replacing these solutions two types of baths, i.e. weakly acid chloride baths and alkaline zincate baths are in competition.
The advantages of the weakly acid chloride baths for zinc coating resides in deposition of highly decorative to brilliant coating, cathodic efficiency almost to 100 % and a very good covering power, that enables even a successful coating of members with a very complicated surface. A disadvantage resides in the distribution of the thickness of the zinc coating in dependence on the local current density.
Alkaline baths for zinc coating suffered from the beginning from deficiencies that restricted their quicker introduction into industrial praxis. Among the greatest of
them a restricted range of current densities allowing deposition of acceptable coatings may be mentioned. There has also been a tendency for blistering and a slow formation of the coating. Formation of coatings with an appearance comparable with that deposited from weakly acid baths has never been achieved.
From the beginning of the evolution of cyanide-free baths for zinc coating a great attention has been focused on the nitrogen polymers that often contained quaternary nitrogen. For example US Patent 3 824 158 protects reaction products of ,,aminated" polyepichlorohydrin with epichlorohydrin with respect to the quaternary character of the active compound. According to US Patent 3 853 718 polyalkyleneimme is modified with the aid of ammonium alkylhalogenide and US Patent 3 869 358 describes quartermzation of dimethylaminopropylamme with the aid of epichlorohydrin .
In further patent documents quaternary oligomers and polymers are synthetized with the aid of heterocyclic monomers . Of these monomers epichlorohydrin and aliphatic amine (US 3 974 045, US 4 397 717, US 4 730 022) or only epihalogenhydrin or glycerolhalogenhydrin (US 3 954 575 or US 4 045 306) can be named.
An important progress has been achieved by the use of polymers that contain N, N-bis [3- (dialkylammo) alkyl] urea as their basic monomer. For the synthesis of active compounds it is then possible to use polymeration with the use of various chlorinated dialkylethers (US 4 157 388, US 5 405 523, US 5 435 898) or dihalogenalkans (WO 00/014305) or with the use of dihalogenalkans and tertiary diamines
(US 6 706 167) . The advantage of these processes resides particularly in the very good homogenity of the thickness of the layer that is produced from the zinc plating baths with the use of the polymers mentioned above. During the zinc plating it is, however, still not possible to attain sufficient gloss of the coating, the shade after brightening and chromate treatment is deeper and less brilliant than that of the coating produced from weakly acid baths. The rate of production of the coating is also relatively low due to the lower efficiency of the cathodic process .
All these disadvantages may be suppressed by the nitrogen polymer additive, a process for producing this additive and the use of this additive in alkaline baths for zinc and zinc alloy coating according to the present invention.
Summary of the invention
The invention resides in the nitrogen polymer additive for electrolytic zinc and zinc alloy coating of formula I
(I)
wherein
Z means CH 2 -CH(OH)CH 2 or (C r H 2r ) -0- (C r H 2r ) or C q H 2q , wherein r = 1 to 6 and q =1 to 6, a = 0 to 1, b = 0 to 1, a + b = 1, x = 0 to 1, y = 0 to 1, x + y = 1 and n is at least 2, R, Ri, R',R ' i independently mean C m H 2m +i wherein m = 1 to 3 or -CH 2 OH or -CH 2 CH 2 OH or -CH 2 CH(OH)CH 3 or -CH 2 CH(OH)CH 2 OH or may be identical, R 2 means (CH 2 ) c wherein c = 2 to 6,
R 3 means C=O, C=S, C=NH or O=C (CH 2 ) d C=0, wherein d =2 to 6, R' 2 means (CH 2 ) g , wherein g = 2 to 6 and
R ' 3 means C=O, C=S, N=NH or O=C (CH 2 ) h C=0, wherein h = 2 to 6, as a reaction product of at least one amino derivative of general formula II
(H)
and at least one amino derivative of general formula III
(III)
wherein all general symbols used have the meaning stated above, with at least one halogen derivative from the group of epihalogenhydrin and/or 1, 3-dichloro-2-hydroxypropan and/or dihalogenalkane of general formula X-(C q H 2q )-X, wherein q=l to 6 and X means Cl, Br or I and/or dihalogenalkylether of general formula X- (C r H 2r ) 0- (C r H 2r ) -X wherein r = 1 to 6 and X means Cl, Br or I.
A direct reaction of the monomers may be performed in an aqueous or in a suitable organic medium. In the reactor an appropriate amount of monomers of formulas I and II is firstly dissolved in a suitable solvent and then the halogen derivative is added step by step in such a manner as to avoid a too vigorous reaction. The nitrogen monomers of formulas II and III are added in a molar ratio of 100:0 to 0 : 100. For 1 mol of the mixture of the nitrogen monomers 0,5 to 1,5 mol, preferably 0,8 to 1,2 mol and most preferably 1 mol of the halogen derivative is used. The range of possible reaction temperatures is 20 to 180, more preferably 80 to 120 0 C in dependency on the reaction components used. The reaction can be well performed at the reflux temperature. The typical reaction time is 1 to 48 hours and is dependent on the reaction components used.
The reaction conditions are selected to obtain a copolymer with alternating units of monomers described above with a molecular weight of the product of 300 to
1 000 000, preferably 1000 to 10 000. Positively charged quaternary nitrogen atoms are regularly repeated in the final chain. The process for producing of the nitrogen polymer additive according to the invention allows changes of the charge density by selection of monomers and so an accurate optimalization of the features of the additive in dependency on the features of the bath and with respect to the final coating is possible. The polymer produced is polycationic, therefore, for this reason in the electric field it is drawn to the cathode and there it intensively influences further cathodic processes, especially electroreduction of metals (Me x+ -xe ~ — Me) .
Nitrogen polymer additives thus produced are added to alkaline baths for zinc and zinc alloy plating that contain
2 to 50 g/1, more preferably 8 to 15 g/1 of Zn and further 10 to 300, preferably 90 to 160 g/1 of NaOH and/or KOH and/or LiOH, the additives of formula I may be used individually or in combinations. Metal Zn or ZnO that is dissolved chemically or electrochemically in a solution of alkali hydroxide or another soluble zinc compound may be used as a source of Zn. The bath may also contain carbonate ions in an amount of not more than 100 g/1. The nitrogen polymer additive according to the invention is added to the bath in an amount of 0,1 to 20 g/1 (of the active compound) . For deposition of zinc alloys complexes of Fe, Co, Ni or Mn may be added in an amount of 0,01 to 50 g/1. Further it is possible to add compounds that eliminate water hardness and metal impurities as silicates, polyhydroxy acids (tartrate, gluconate etc.) or other
complexes forming compounds (EDTA) in an amount of 0,1 to 100 g/1. It is also possible to add further nitrogen oligomers or polymers for refining crystalline structure of the coating, e.g. reaction products of imidazole, morpholine or piperazine with epichlorhydrin and an aliphatic amine in an amount of 0,1 to 20 g/1. The gloss in the range of low current densities may be ameliorated by compounds containing divalent sulphur as Na 2 S, thiourea and its derivatives or heterocyclic compounds containing the group C=S (as imidazoline thion) . These compounds are added to a concentration of 0,01 to 5 g/1. Gloss, levelling and brilliancy may be influenced by aromatic aldehydes (vanillin, heliotropin, anisaldehyde) and further aromatic compounds (benzylpyridinium-3-carboxylate) , in an effective concentration of 0,001 to 1 g/1. Electroplating is performed at a temperature of 10 to 60, preferably 20 to 30 0 C, with the use of steel anodes, zinc anodes or nickel coated steel anodes.
From such baths it is possible to plate zinc or zinc alloy coatings with a number of advantageous features. The coatings produced for example have fully homogenous thickness also on very complicated parts, a high brilliant gloss, comparable with that plated from weakly acid baths and sufficient drawability without tendency to produce blisters. At the same time the baths retain their current efficiency that in the industrial praxis enables a more effective work than with the use of known technologies. The invention will now be illustrated by working examples that are not intended for restricting the scope of the invention.
Examples 1 to 4 (process for producing the nitrogen polymer additive)
Example 1
32,6 g (0,2 mol) of N- (3-dimethylaminoethyl) urea and 4,3 g (0,02 mol) of N, N ' -bis (3-dimethylaminoethyl) urea was dissolved in a mixture of 20 ml of water and 10 ml of ethanol, to this solution 24,8 g (0,22 mol) of 1,3- dichloropropane was added and the reaction mixture was refluxed 6 hours, then diluted by 30 ml of water and the reaction product was filtered off with the aid of charcoal. 120 g of a water solution of the polymer with a concentration of about 50 % was obtained.
Example 2
0,41 g (0,002 mol) of N- (3-diethylaminobutyl) thiourea, 2,6 g (0,018 mol) of N- (3-dimethylaminopropyl) urea and 56,5 g (0,18 mol) N, N ' -bis (3-dipropylaminopentyl) urea was dissolved in 100 ml of THF and to this solution 18,5 g (0,2 mol) of epichlorhydrin was added and the whole mixture was refluxed 12 hours. Then THF was distilled off under reduced pressure, 40 ml of water was added and the mixture was filtered with the aid of charcoal. 100 g of a water solution of the polymer with a concentration of about 60 % was obtained.
Example 3
29 g (0,2 mol) of N- (3-dimethylaminopropyl) urea, 5,9 g (0,02 mol of N, N ' -bis (3-dimethylaminopropyl) thiourea and 39 g (0,18 mol of N, N ' -bis (3-dimethylaminoethyl) urea was
dissolved in 100 ml of water and to this solution 57,2 g (0,4 mol) of dichloroethylether was added and the reaction mixture was refluxed 24 hours. Then 200 ml of water was added and the mixture was filtered with the aid of charcoal .
4000 g of a water solution of the polymer with a concentration of about 30 % was obtained.
Example 4
26 g (0,18 mol) of N- (3-dimethylaminopropyl) urea, 3,22 g (0,02 mol) of N- (3-dimethylaminopropyl) thiourea and 46 f (0,02 mol) N, N ' -bis (3-dimethylaminopropyl) urea was dissolved in a mixture of 20 ml of water and 80 ml of ethanol. To this solution 56,4 g (0,4 mol) of 1,5- dichloropentane was added and the reaction mixture was refluxed 16 hours, diluted by 330 ml of water and the reaction product was filtered off with the aid of charcoal. 530 g of a water solution of the polymer with a concentration of about 30 % was obtained. Examples A - D (Use of the nitrogen polymer additive) : The advantages of the baths prepared according to the present invention may be evaluated for example according to CSN 03 8530 (Electroplating in the Hull's bath).
Example A
Basic zinc-plating solution: 12 g/1 Zn 120 g/1 NaOH 20 g/1 Na 2 CO 3
Anode: nickel coated steel anode
current: IA for 15 minutes
1,5 g of the polymer of Example 1
20 mg/1 BNC
20 mg/1 vanillin
after brightening in 0,5% nitric acid for 5 seconds a brilliant coating has been obtained without fog with a brilliancy comparable with that produced from weakly acid baths. The thickness of the coating was 2,5 cm from the higher current densities (point B) and 2,5 cm from the low current desities (point A). B/A 1,2 B+A 15,5.
Example B
Basic zinc-plating solution: 12 g/1 Zn 120 g/1 KOH 20 g/1 K 2 CO 3
Anode: nickel coated steel anode current: IA for 15 minutes
0,5 g of the polymer of Example 2
50 mg/1 BNC
20 mg/1 vanillin
after brightening in 0,5% nitric acid for 5 seconds a brilliant coating has been obtained without fog with a brilliancy comparable with that produced from weakly acid baths. The thickness of the coating was 2,5 cm from the higher current densities (point B) and 2,5 cm from the low current desities (point A). B/A 1,15 B+A 15,8.
Example C
Basic zinc-plating solution: 12 g/1 Zn 120 g/1 NaOH 20 g/1 Na 2 CO 3
Anode: nickel coated steel anode current: IA for 15 minutes
1,5 g of the polymer of Example 3
50 mg/1 benzylpyridinium-3-carboxylate
20 mg/1 vanillin
after brightening in 0,5% nitric acid for 5 seconds a brilliant coating has been obtained without fog with a brilliancy comparable with that produced from weakly acid baths. The thickness of the coating was 2,5 cm from the higher current densities (point B) and 2,5 cm from the low current desities (point A). B/A 1,25 B+A 15,4.
Example D
Basic zinc-plating solution:
12 g/1 Zn
120 g/1 NaOH
20 g/1 Na 2 CO 3
50 mg/1 Fe
30 g/1 natrium gluconate
Anode: nickel coated steel anode current: IA for 15 minutes
1,5 g of the polymer of Example 4
50 mg/1 BNC
20 mg/1 vanillin
after brightening in 0,5% nitric acid for 5 seconds a brilliant coating has been obtained without fog with a brilliancy comparable with that produced from weakly acid baths.
Test for adhesion of the coating: a)
Basic zinc-plating solution:
12 g/1 Zn
120 g/1 NaOH
20 g/1 Na 2 CO 3
Anode: nickel coated steel anode current: IA for 40 minutes
1,5 g of the polymer of Example 1
50 mg/1 benzylpyridinium-3-carboxylate
20 mg/1 vanillin
the coating produced was subjected to a heat shock at a temperature of 10 0 C for 5 minutes. Then the coating was quickly cooled to room temperature and followed up for further 14 days. Production of blisters was not observed.
b)
Basic zinc-plating solution:
12 g/1 Zn
120 g/1 NaOH
20 g/1 Na 2 CO 3
Anode: nickel coated steel anode current: IA for 40 minutes
0,5 g of the polymer of Example 2
50 mg/1 benzylpyridinium-3-carboxylate
20 mg/1 vanillin
the coating produced was subjected to a temperature of 70 0 C for 14 days. It was not possible to observe any production of blisters.
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