DE1621551A1 - Process for degreasing and / or derusting metal surfaces - Google Patents

Description

Cööperatieve Verkoop "en Productievereniging Aardappelmeel en Derivaten ¹¹ AVEBE"'Cf ₀ -AVj Yeeridai% Netherlands

.-. ■ ■ - ■, "or λ ■ · '-: '" -, ■■ '..- "Process for degreasing and / derusting" metal surfaces ""

The. Present look refers to a method of ^^ degreasing and / or removing rust from MetallflächeB · metal parts iaa "often ben oil. Grease or dirt on their Oiaerflaolien ^ which only needs to be _a walk before these metal parts s © Hütz © ndem treatments, such as painting, Electroplating (electroplating) or coating with an enamel ^ '-subjected -.- are _: can _ö - ·

For this degreasing - largely * aXlcalisöltä, BEder uses - the alkali saponifies di © ■ / fatty- T # rtiai »e3aigjmge8ip.- as far as they are of vegetable origin ~ s-ind _o mineral oils-" wa3? DeEi - "; la \"'d0r ■ hot alkaline EÖaiang. eBRilgierto Ik many. Fülea is an alkaline' degreasing bath .in Koa? binatlG> Ä mife der Amiegiiog a positive, (anodic) "" odes? - H @ gati ¥ «a. --β, aa dgn ^ u purifying
electrolytic

is marked as s & h ^ a ^ kB & h »- Ofeerfläehefefeeaaödlipig tone . >

It was found that this degreasing, itiifc run one. elektriselien .Btroffis-: erhebliGh can if the alkaline bath one. Salt © the Polyhydroxycarboxylic acid has at least two to @ n & aiite @, rt @ n Hydroxyl groups added

In general, the fat layer also contains rust *. xflfar © ni sloh

ö δ 51/1841; . ■■ - ■ - ■

under the layer of fat a firmly adhering to the surface

Types of
In order to remove this food at the same time as the fat, alkali metal cyanide can be added to the alkaline degreasing baths. Excellent results are obtained with these baths, but they have the disadvantage that they are very toxic «

Surprisingly? Tired of finding that degreasing and / or derusting metal surfaces are equally good results can be achieved if alkaline baths are used which contain a salt or a laetone of a polyhydroxycarboxylic acid contain. In this way, the use of a poisonous alkali anide for rust removal can be completely avoided.

To remove rust from grease-free metal surfaces, you can also alkaline solutions of a salt or lactone of a Polyhydroxycarbonsaur® successfully used according to the invention will ^

The subject of the invention isfc demgtaaiäss © in a process for Degrease and / or J & ifeEOstda iron M @ t®llf! See with alkaline

^/ G is ,, that m & M. @ ± n @ v Polyhydroxycär «

fooic acid lait w © nigsfc © a @ i? i? © i © © naelifea ^ t® »I- ^ arosqrlgruppen

Iö iä ICombi «»

AIe Lastoae oö @ r Sals © -worn Foi

Alksliglueonate oäer Hi & aliglmoteptpaafe © 'k räsohtnderweis © has sung Jedooh _ö öag © © isi @

Combination of these »SEui» ®is. with SaX & mi 4 © 3? Acid ©

1/1641

Very good results are obtained when boron gluconate (* 'Pasexon looB ^M ) is added. This is a boric acid "complex of Natriumgluoonat obtained by adding about Jo parts borax decahydrate to loo parts Natriumgluoonat than 5o #ige solution in water and the solution in an atomizer drying · Of course, the favorable influence of boric acid and its salts on the effect of polyhydroxy «

not

carboxylic acid limited to the ratio that is present in the above product products can be used in which the molar ratio of gluoonate to boric acid is at least 0.5: 1, preferably more than 1: 1

It is not entirely clear why boric acid and its salts have a beneficial effect here, because it is not evident that boric acid complexes of polyhydroxyoarboxylic acid are visibly differ significantly from the corresponding polyhydroxycarboxylic acids in terms of degreasing

It is of course possible that gluconate and boric acid or one of its alkali salts separated from the starting solution from which the bath liquid is produced, or from the bath liquid « ability to give oneself. Trooken mixtures of polyhydrocarboxylic acid salts and boric acid salts can of course also be used.

Sometimes it is desirable for other purposes to use a combination of boron gluoonate with a polyaminocarboxylic acid in order to achieve maximum cleaning action. In a degreasing and derusting bath used for experiments, in which mostly 50 % of the boron gluoonate was replaced by EDTA (ethylenediaminotetraacetic acid), - in general, no improvement was achieved compared to the results obtained when boron gluconate was used exclusively. Although such a replacement when using a hot alkali solution resulted in a slight improvement when the metal plates to be degreased with trichloroethane

009831/1641

• SAD

were pretreated and the degreasing activity of the alkaline bath when passing through an electrical Current was increased. However, without the application of a current, the results were less favorable, even after one Pretreatment with trichloroethane. In various experiments the results were obtained with a combination of Boron gluconates and E.D.T.A., better than those obtained with sodium gluoonate. When degreasing with alkali without applying an electric current and without pretreatment is made with trichloroethane, a bath is preferably used which contains 5 - 20 g of sodium gluconate or contains a boric acid complex of sodium gluconate per liter. After a pre-treatment with trichloroethane preferably a bath that uses 5 - lo 'g of sodium gluconate per liter contains.

PUr alkaline cathodic or anodic degreasing in the cold is preferably used a bath containing 5-25 g / l of sodium gluconate of a boric acid complex or a Combination of these compounds contains. For removal with a hot bath without the use of an electric bath Stromes or for the cathodic removal of light - Rust is preferably used a bath that is 5 - 25 g Sodium gluconate per liter contains * PUr the removal of heavy rust by cathodic means or without application an electric current, a bath is preferred which contains 50 - 100 g sodium gluconate per liter.

A bath of the following composition was used for degreasing s

HaOH "Tensagex 45 g / i Ka ₂ CO ₃₈ OI ^ O 25th g / l Na ₃ PO ^ OHgO ! 09831/1 25th g / l Dispersants DP 24 ^8β ο, 9 g / l 64 1

Various parts of this bath were O ₀ 5, lo, 15, 2o and 25 g of sodium gluconate "Each bath was used at a temperature of 96 ~ 98 ⁰ C with and without passing an electric current · The electrolytic treatment was both anodic and cathodic carried out at a current density of 6 A / dm. Since this bath is used at a fairly high temperature, while air is blown in to intensely agitate the liquid, the sodium hydroxide is constantly being converted into sodium carbonate:

2 NaOH + CO ₂ £> Na ₃ CO ₃

In order to avoid side effects in the experiments and to compare " To obtain real values, the bath was renewed when the sodium carbonate concentration had risen to 40 g / l «,

Further experiments were conducted with a bath durchgefüiirt the _# 5o g of NaOH and 0.8 g of "DP 2 Bensagex dispersant ¥ ^l per liter would contain This bath was applied at a maximum temperature of J55 ° C · To portions of this bath were 0, 5, lo, where 15, or 2O x 25 g per liter of sodium gluconate. The bath was replaced with a Natriumoarbonatgehalt of 15 g / l. In this bath was both anodically and cathodically degreased at a current density of] 5 a / dm <

For experimental purposes, steel sheets of 15 x 15 cm were treated. In order to obtain a uniform starting product, these sheets were pretreated as follows;

1) Degreasing with trichloroethane

2) Wipe with a clean rag

^) Oil with a rust protection © *! ("Ensis 295 ^W ) if) Drying for at least one day

00 98 31/1841 bad original

· * O «ν

All experiments were carried out in a bath of 2oo 1. The point at which the degreasing process ends was assumed in which the water film no longer "broke" after rinsing. the The time to reach this end point was a measure of the degreasing capacity of the bath

As an additional test of the degreasing ability, one sheet of each group of Io sheets was then nickel-plated. With this nickel-plated sheet, the adhesive strength was tested according to the Erichson-Tesf. If it turns out that the Adhesion strength was insufficient, the whole group became of Bleohen treated again in a freshly made bath.

A test with Io Sheets after pre-degreasing with trichloroethane and with Io sheets carried out without degreasing with triehlorethane. The results obtained are shown in the table below.

BATH

009 8 31/1841

Treatment time in seconds by operation

Gluconate content of

degreasing bath, 0 5 Io 15 2o 25 g / l

Hot alkaline bath without power supply and without prior degreasing with

Triohlorethane 45oo 690 627 486 360

Hot alkaline bath without power supply * previous Degrease with triohlorethane 24ö 30 15 15 2o

Hot alkaline bath, anodic treatment without prior degreasing

with triohlorethane 222 21o 192 I98 213

Hot alkaline bath, anodic treatment, prior degreasing with

Trichloroethane 33 30 15 12.5 8

Hot alkaline bath, cathodic treatment without prior degreasing

with trichloroethane I80 I80 15ο Ι50 93

Hot alkaline bath, cathodic treatment prior degreasing

with triohlorethane 2o 15 2o Io 8

Cold bath containing gluconate, anodic treatment, previous degreasing with

Trichloroethane 600 300 12o 90 60

Cold bath containing gluconate, cathodic treatment without prior! " total degreasing with TrI-

chloroethane 72o 42o 360 2Jo 24o

Cold bath containing gluconate, cathodic treatment, prior degreasing with trichloroethane 12o 60 '3o 15 Io

009831/1641

Example 2
This example describes rust removal attempts "

For the treatment of lightly rusted surfaces a bath at 9O ⁰ C was used containing, per liter, 50 g NaOH and SS

? B ^? contained .. To share this

Baths were 10, 20, 30, 40 and 50 g of sodium glueonate per Liters given.

For the treatment of heavily rusted surfaces a

Bath at 90 ⁰ O used, the per liter 250 g NaOH and additional «specific

borrowed 2 g of the dispersant "Tensofene D 42" concentrate contained. 50, 60, 70, 80 and 90 g of sodium gluconate per liter were added to parts of this bath.

These tests were carried out in a bath of 200 liters. 10 sheets were treated for each Versuoh. The one for removal The time taken for the grate was a measure of the effectiveness of the bath. After the treatment, it remained a bit shorter Dust film on the heavily rusted sheet metal · This film however, completely disappeared upon subsequent acid immersion and had no adverse influence on the Adhesion strength of a deposited! Coating.

Here, too, uniform initial conditions were created. For this purpose, the sheets to be derusted were designed as follows pretreated "

1) Degreasing with trichloroethane

2) Degrease with a hot alkaline bath for 1 minute without power

3) Cold rinse

4) Immersion in hydrochloric acid 1: 1 for a period of 15 seconds

5) Cold rinse

The metal sheets were then placed in a cabinet in which a relative humidity of about $ 80 and a temperature of 38 ^° C. were maintained. _O In this cabinet

ODQOOi / 1 (J / 1

. ' "· - BAD ORIGINAL

the lightly roasted trays 10-20 minutes and the heavily toasted sheets held for 48 hours

The derusting was done both without power supply and cathodic A current density was made in the latter pail of 30 i / dm applied. Here, too, each group became a sheet is then nickel-plated and the adhesive strength as well as those tested in the degreasing tests. The following results were obtained in these tests »

How it works Treatment duration in seconds

Grluoonate content of the rust removal bath. gA 1Q 20 30 4-0 50

Hot alkaline bath, none

Power supply, light loose layer 240 120 90 60 30

Hot alkaline bath, cathodic treatment, light
Grate 60 30 10 5 2

Grluoonate content of the rust removal bath, g / l ; 50 60 70 80 90 100

Hot alkaline bath,

no power, strong

Hosts not "300 120 90 60 45 30 Hot alkaline bath,

cathodic treatment 120 30 10 5 1 0.5

Comment; When derusting in a bath, that's only one solution of sodium hydroxide, no useful results were obtained.

Example 3
This example describes degreasing attempts _{or similar}

The basic composition of that used for hot degreasing Bath was the same as in Example 1 «The bath temperature was 96-98 ° G · to file the bades wuy & en aa- place of Sodium gluoonate equal to © feiiiehsmengea.- (1s © s @ g®a a, ia, f

9831/1

- Io -

Solid) given a boron gluconate, which by reaction of 35 kg of borax decahydrate with a solution of 100 kg of sodium » gluoonate (dry pesticide) and drying the reaction mixture was obtained · Otherwise was on the same Worked as in Example 1.

For degreasing with a cold bath, equivalent to more or less a final degreasing in practice, the basic composition of the bath was also the same as in Example 1. Tn this case, however, the sodium gluconate replaced by an equal amount by weight of Borgluconats. The tests without prior degreasing with trichloroethane when using cold baths were not repeated in this test series because this does not correspond to normal practice. The results obtained are summarized below:

8S31 / 1S4! -

Treatment time in seconds by operation

Boron gluoonate content of
bath used for degreasing g / l 0 5 15

Hot alkaline bath, 'none
Power supply no previous degreasing with triohlorethane 45oo 42o 24o I8o

Hot alkaline bath, none
Power supply prior degreasing with triohlorethane 24o 35 3o 1

Hot alkaline bath,

anodic treatment no

previous degreasing with

Trichloroethane 22o 9o 9o 9o

Hot alkaline bath,
anodic treatment with prior degreasing
Trichloroethane 35 15 8 2

Hot alkaline bath,
cathodic treatment, no
previous degreasing with trichloroethane I8o 35 17 15

Hot alkaline bath, cathodic ©

Treatment, previous treatment

greasing with trichloroethane 2o 7 6 1

Cold bath containing gluoonate,
anodic treatment, prior degreasing with
Trichloroethane 6oo 6o 25 Io

Cold gluoonate containing

Bath, cathodic treatment,

previous degreasing with

Triohlorätnan 12o 3 © 17 6

- © AD 009831/1641 "~ '

Example 4

This example also relates to a degreasing test and is carried out in exactly the same way as in Example 3 with the exception that instead of the 100% of the boron gluconate mentioned in this example, a combination of 70 % of this boron gluconate and 30 % of this disodium salt or ethylenediaminetetraacetic acid (EDTA) is used.

The results obtained are mentioned in the table below:

009831/1641

-13-Mode of operation Treatment duration in seconds

Degreasing bath that has a boron gluoonate content

from g / l 5 15 25 g / l

Hot alkaline bath «none Power supply without prior

Degrease with triohlorethane II76 784

Hot alkaline bath, no power supply, previous degreasing with triohlorethane 48 54

Hot alkaline bath, anodic treatment without prior degreasing with triohlorethane 336 294

Hot alkaline bath, anodic treatment, previous one Degrease with triohlorethane 6 3

Hot alkaline bath, cathodic treatment, without prior degreasing with

Triohlorethane 112 Io4

Hot alkaline bath, cathodic treatment, previous degreasing with triohlorethane 6 3

Cold gluconic bath, anodic treatment, previous one Degreasing with trichloroethane 33 24

Cold bath containing gluoon, cathodic treatment, prior degreasing with

Triohlorethane 66 44

009831/1641 bad original

Claims (1)

Claims 1. Process for degreasing and / or derusting metal surfaces with alkaline baths, if necessary under Carrying out an electric current, characterized in that one uses baths that contain a salt or Lactone of a polyhydroxycarboxylic acid with at least two neighboring hydroxyl groups and / or their boric acid complex, if desired in combination with a polyamino contain oarboxy carboxylic acid. 2 »Method according to Claim 1, characterized in that a bath is used that contains a salt, laoton, or boric acid complex of D-gluoic acid and at most the same weight content of a polyaminooarboxyoarboxylic acid contains j $. Process according to Claim 1, characterized in that, one used a bath containing sodium jum gluoonate 4. The method according to claim 1, characterized in that a bath is used which contains a boric acid complex of sodium gluconate or a combination thereof with sodium gluoonate. 5. The method according to claim 4, characterized in that the boric acid is added as such and that the complex contains between 0 and 2% boron. 6. The method according to claim 4, characterized in that the Gluoonate or glucon lactone and the boric acid or a salt this can be added separately to the stock solution. 009831/16 / »! f. The method according to claims 3 or 4, characterized in that for the hot degreasing with alkali without applying a electric current and without pretreatment with triehlorethane a bath is used that contains 5 to 20 g / l sodium gluoonate, contains a boric acid complex of sodium gluconate or a combination of both. 8, method according to claims 3 or 4, characterized in, that for hot degreasing with alkali without applying an electric current but with pretreatment with trichloroethane a bath is used containing 3 to 10 g / l sodium gluoonate, contains a boric acid complex of sodium gluconate or a combination of both 9. The method according to claims 3 or 4, characterized in that For alkaline cathodic or anodic degreasing in the cold, a bath containing 15 to 20 g / l sodium gluconate is used, contains a boric acid complex of sodium gluconate or a combination of both Io · The method according to claim 1, characterized in that for hot alkaline, cathodic degreasing a bath is used which contains 3 «15 g / l of a boric acid complex of Oluconic acid contains 11 · The method according to claim 1, characterized in that for helsses alkaline degreasing after a pretreatment with Trichloroethane is used in a bath that is 3 - Io g / l one Combination of a boric acid complex of oluconic acid and E, D. T * A. Contains, the combination of less than 50 wt. ^ E.D. T.A. consists. 009831/1641 SAD ORJGJMAL 12. The method according to claim J, characterized in that that for hot cathodic removal of light rust or for degreasing light rust without penetration « conduction of a current a bath is used that contains 5 ·· 25 g Contains sodium gluconate per liter Method according to claim 3, characterized in that for cathodic removal of heavy rust or removal of heavy rust without passing a current through a bath that 5o - loo g of sodium gluconate per liter contains. 009831/1641