DE1496915A1 - Process for applying a zinc phosphate coating containing metallic zinc to an iron surface - Google Patents

Description

U96915

■ otallgeaellaahmft femakfmrt (MHm), 3rd iifwt 1965

Share «g« »ell # chaft Brlr / BX Franked (KaIm)

vrov. Mr. 4474

The process involves applying «la ·· containing metallic zinc llnkphoaphatüberiugoa on an iron surface

Si · Formation of τοπ protection transfers on iron surfaces, i. H. on surface "that stands on gams or predominantly on iron b", through Behaadlu "g *" r surfaces "with a zi" kfhoephatlös "g belongs * ur etandigen pr axle in -many surface finishing processes. Normally, the treatment becomes old the ZlnkphoephatlOeuMf duroh immersion · »of the surfaces in the ventilation or duroh Sprits · »the Lasuag carried out on the surface. The formation of the bermugee occurs with the acid attack on daa Metal related »and if eiae Phoapkatechioht eich on which metal has formed, largely prevents one further attack, and the Uberavg did then completely. Si Period of time in which a complete (fWrsug calibration, iat different, for example about one minute with a typical solution that is used in spraying, and 5 minutes with a typical solution into which the iron surface is immersed will·

UberiUg ¹ · are however, aelbat v «am they are very fine-grained, to a certain extent porous and are therefore effective as such

no full Korroaiomaeehut. % m iat therefore Oblioh,

909846/0823

BATH ORIGINAL

U96915

cover them with varnish or oil. SI «are used to the greatest extent * as a basis on which a lacquer coating is applied, and« was especially intended to convey the strength of the LaCk ₁ but also, among other things, to cause a certain degree of corrosion protection under the lacquer layer.

The latest development in paints based on water-soluble binders has led to the use of such paints Electrophoresis performed, which is now of greater importance is · With the electrophoretical application of lacquers play both electroosmotic * and electrolytic as well electrophoretically «gates a Boll ·. In this case an electric stroa is sent through the Laek, and that The workpiece to be painted is connected in the paint as an electrode, as an anode.

LimkphosphatUbersÜge, which are produced according to the Ubllohen dipping or spraying process, are, however, as Orumdlage, on the a lacquer should be applied electrophoretically »not completely satisfactory, since it has a considerable electrical effect .: Have resistance. This can be beneficial surr: Ensuring a good distribution of the electrophoretically applied paint. However, he can change the thickness of the varnish, that can be applied. The high resistance and thus the low conductivity of the XinphoephatUbersuge can therefore lead to the difficulty of electrophoresis lie Laokttbersttge an ama required starry *

909846/082 3

_ ₃ _ H96915

Apply thickness. Venn paint electrophoretically on one If the usual crystalline zinc phosphate oversug is applied, an oil loss also occurs.

£ ■ »« is therefore the wish for «in ·· procedure sur of xinkpheephat coverings, dl «« «anyway without laughing at you have good corrosion resistance, no loss of flans of subsequently electrophoretically applied paint lead and which have a controlled electrical resistance exhibit.

It has been known for a long time that zinc phoephate is absorbed by Treatment τ on iron surfaces with a sink phosphate · » solution deposited under application in «r« l «ktri tension will know.

From US patent Ir. 1 856 261 it is known that the Initiate the formation of a dense, black zinc phosphate supersugea by the application of an electric current and then switch off the electricity and the phosphating as in a « normal diving fortsuaetsen. Aue of this patent specification is ee also known to monitor the current intermittently » In this known method, the electrolytically deposited zinc is converted into zinc phosphate, so that the generated Overalls have a high resistance. In addition, seigen such inevitably overshadowed the power that it su one Olanrrerluet lead the subsequently applied paints. at

909346/0823

de * In the OÖ-PateAtachrift Ir. 1 856 261 described · * Τ · γ-driving was necessary, haha use concentrate on Phpayüat au, for example 5 to 8 f> _$ and the free part of the coating solution Ia narrow size, r. B. amf 0.05 Ma 0.13 *, xu hold.

feaaf & · χ Torliagandaii KrfiadvBf a rubble over «* aaf • iaer alaffraen surface is applied in xvti steps. XuBaehat is brought dta surface oknt StroBanwe & duB ^ old one overa ^ ablldemdea SliücphoaphatlttauAg Ia contact, bia eieh the IlnkfhoapftatObarsug! ■ weaeatlichen has completely fablXiat. Then, the old coating dta veraehene surface Ia is a ttbariEUfablldenden ZlnkphoaphatlBaung ale cathode g · - eohaltett ao that zinc is deposited. The zinc is mainly deposited in the puddle of metal and becomes aloh sunXchet in the pores of the original zinc phosphate coating.

They deposition of metallic "zinc lead tu a Irniedrlgung dee elektrlechen Wlderetandee of the coatings, and diee" eight eie suitable Oroindlage ale, can be applied to the paint by an electrophoretically ^ procedures. Pie well, the process of the invention resulted in an extremely smooth finish, and the coating of varnish applied to it was much higher than it was normally given a customary crystalline phosphate coating of brazed laok. The Aeeoheiduag also leads this

909846/0823

BATHROOM ORIGINAL - 5 -

-5- H96915

Betall isehwa Slmk au sitter TerseiMeruag A ·· Korroaionsvlderstandee the overseas, and "was like a mere state of being auaA with subsequent electroshore or other Laokleraag,

The method according to the invention can be found under Y «rw« Ad \ mg «liier Üii * rr \ tc * l> lld« ndtn LO »vag door dl · ereto Sohlchtbilduag and • lA» r hl * ZTOB vtmoAlAdvntn Xiiücflu »sphAtlBftang fCLr dl · tlelrtro-17tlach · AiBoteldaxig tob Zink duroh ^ efükrt v «rdux. Torettg »- w« l »· becomes j« doeh dl · β1 · 1οή · LOtUBg la teidtn 8tufra Y «r« w «Bd« t. Si ·· let ) f * m *** T * ivttmtlkAtt, Aa then only · 1η · · 1βι1 «·

»Rou« kt.

The treatment aur Atutblldong d. PhoafhatUberaogea can be in any degree of success. Ib labjMA d "inventionag ^ BaAeB Y" rfahr * na let "In" T uohbehaBdlvng ¥ "special sweekaällg, since ea then only required i *%, that the workpiece sur surface treatment is provided on a bit of an electrical line _en carrier in the phosphating solution bring bu and turn on the atroe when the uberxug la essential is complete. üs is JedooB auoh adglioh, the treatment Ib wpritaen duroheufUhren. Sae workpiece can then be passed through the spray zone in the usual way of treating the surface of a conveyor blade and by connecting the conveyor bit to an electrical line, the current of which is switched on while the workpiece is in a leaflet containing air is immersed. 11b · there is further possibility

909846/0823

U96915

in it, the work which has been provided with an essentially complete coating by conventional spray treatment electrical line to be connected cathodically and to flood with the solution until the desired deposition of metallic Zinc occurs 1st.

Although there is a distinct advantage of the inventive method is that the two treatment stages can be carried out in only one solution tank, is the application from separate solution containers, each of the containers of course a coating-forming zinc phosphate solution contain oni, which preferably have the same composition exhibit. The disadvantage of such a procedure, however, is that both baths must be monitored separately.

In the method according to the invention, all zinc phosphate solutions, those used to form protective coatings on elsens Surfaces are usable and all common cleaning and rinsing treatments are used. The phosphating solution usually contains an accelerator and has been found to be the accelerator used affects to some extent the type of coating formed. For example, if the accelerator litrat let and the solution contains ferrous ions or if the accelerator is litrite together bit or without litrat, will be dark gray coatings received. However, if the accelerator is Chiorat or Peroxide is, light gray coatings are a bit higher

909346/0823

-7- U9691J5

«Β aetalllschea Hak received. I will be general effcatiesvngen, which contain chlorine as an accelerator, . IiB Orvnd for this is · that 41 «Badstdlaguag ·«

somewhat less critical »lad ¥ # 1 dl · ··« oxidizing agent.

Bi * conditions, then carried out under dl raogshetBohlohtauabllduag and dl «Uakabechoiduog, influence the otter suf obtained. Al · oytlaalen B "dla4 * anc" o ^™ τ · Al j "w" il · aa4 * "w" ad "t · LOsvag kBnnen easily eralttelt by tests · Ia general" AStart is fen the use ΙΛ- wrmmfA, dl «0.5 sls 3.0 % PO ^ contain, beforehand. The content of free PhoajherÄture of the solutions llegf as a precautionary measure in the range of 0.3 hl · 0 _v 8 i>. XIa veiter tea temperature "" rich can be applied. The properties of the Uaerruges are always different depending on the applied ¥ "a * ere% tr and used" Beeohleonlger. High temperatures favor the simultaneous deposition of clay, phosphate and aetallisohsa zinc, especially with litrat and / or Iltrlt as accelerators. Torsugsweise the deposited coating during Strondurchgangs 1 "should weaentllchen from aetallischea zinc consist * From theseA reason Tenperaturtn should not exceed 82 ⁰ C. Boron boTorsugte Teaperaturbereloh is 21 to 71 ⁰ C. The other condition that influences the excess is the surface density that is used during the zinc separation. In general, it is desirable to use a street density that is not higher than 3.3 A / d « ² . The torxugte range is 0.55 to 1.65 A / da ² . The duration of the phosphate layer

909846/0823

• m B «·

The formation and deposition of zinc also depend on it the prevailing conditions. When the procedure la diving is carried out, the current will preferably wipe one tenth of the tent in which the phosphate coating was applied and applied at the same time.

Example 1i

100 g of an aue 120 g of zinc oxide, 375 g of phosphoric acid and water were diluted with water to one liter. The resulting solution had an overall acidity of 3/4 points and a free acidity of 6.0 points. The solution was heated to 66 ⁰ C erv a'rmt / and 1 g Katrlumnltrit added. Steel sheets were immersed in the soldering for 4 minutes and then current was passed through the solution for one minute at a current density of 1.653 A / dm, the sheets being connected as cathodes. The sheets obtained are referred to as "sheets A".

Other steel sheets of the same type were coated with a coating only by immersing them in the same solution for 5 minutes ("Sheet B"). A comparison of the two Blecheerien showed there <3 could be applied to the plates by means of a Λ elektrophoretlachen muddled thicker coatings of water-borne paints "la on the sheets as was the Korrosionowiderstand the plates L ebenfallε Beeeer how to aue

9 C; ^f \ /: B / 0 8 2 3 BAD ORKStNAU

H969I5

the * rgebala * en tob CorroBienBTerevLehea given in Table 1, the 96 standing old unpainted sheets carried out were, results.

lle «b * tal

96 Ib *

2O * iger 100

at

50 * C 96 a ttofttnäek · Ib

2 95

Sfvr

, wit bti 4 «n Bltohen A, vurdoB b« i? ho · - tob 2 minutes or a minute and duration the IlBkBbacheidittg of 30 or 15 seconds onstoll «the with the above A b # Buttten times of 4 minutes and one MiBUte received.

BeUplel 2i

In the example, the properties from to do « Inventive methods of treated bloat »(sheet C) Bit deaen from seeing Terglichea, widening the bit of an Ib QBlan «sur fhoefBatlervB« gate of the Laokiaruse HaBdeleaaliehen Bitrat / nitriteWeehrebslfte * linkpheephat-

909846/0823

bad original

- ίο -

treated wmrdoA (sheet «D) *

Kit BoKBlJi reingeviated sheet steel "(sheet C) were given the Ζιμμημβ-Mfcuof given in Β · 1 ·» 1 · 1 1 at 71 * C Ia «la · ittAVAg. lath oiner MiAat · murd · for 15 seconds oIa Stroa voA 1 _p ft5 A / da «Agolofl. ln «eAll« t «nd the dl« Β1 · βΑ «nit W *« «« rf «« pttlt OAd t * «treokA« t. W «it« r «lloobo varden Ia cl« ioA «r W« l «o» «1 oiAor Ta« obd «u« r you 2 bAw. 4 minutes

AAd llMI StTOAdATOAJAAC VOA i / 2 »AV ·« iA «r JIiAUtO D« hAAd «lt

(11 ο eh «Cl« Ad 04).

SI · Bleeh «S became« A ledlgliok UbIioh "PohaAdiwngmlB-ag

k «i 77 ° Ia the hajUele-

Blaifier Bleeh «Cl, O 2, C4 and P were respectively denoted for f« frflft, vMkr «ad AAder • rox d« r friltwmt old • 1α • α «• 1> • α

AUqrdkAjrA «liAAr« AAlA8k was leeked «. Si «irgekAl · ·· der AiAd ΙΑ Τ · 0 «11 · 2 Wi« d «JTf« g «b« A.

Te »elle Z

Unsullied blanks

Lacquered sheet metal

Sheets

Salt pre-tea 168 k

Roetbe

HelSfeuchtlg JwIt 168 k Boetbe- i * deekaag in 1>

Roet \ int * change

sole · »:
teet 550 \

ie

humidity
η

Blindness la Heiffeuehtlgkelteteat

820 h

5 5

15 95

5 5

5 40

909846/0823

little 6

«« Al * 5

Altt «ldlokt 8« • al «5
altt «ldl« kt β

altt «ldleAt 6

BAD ORIGINAL If -

- ¹¹ - U9B91H

The bloom formation was measured according to ASTM-I) 714.

The UaftfeotlgkeltsprUprüfung showed that the Laok liability on the Sheets C1, C2 and C4 which are the same or only slightly less never only the sheet metal B. Your better corrosion resistance, both lacquered ice also not lacquered, can be seen from table 2.

Example 3i

I) The method of the invention described in Example 2 was repeated, but instead of the solution used in Example 2, a commercially available sink phosphate solution was used which contained chlorate as an accelerator and had a geospatiality of 20 points and a vacancy of 3.0 points . Up to the metal sheets were immersed in the solution for 4 minutes at 71 °, followed by a temperature of 1.1 k / ηη for one minute.

The result was a value of 75 for the trays treated with this method. On the other hand, metal sheets which had also been treated in this solution, but without exposure to electricity, resulted in an oineness bb and, as is customary in the trade, "electrogulvanized sheet metal an" ated of OD. JiaXu Lrichaenl'ensterteot, rods of 1 mm length are cut into the lacquer. The vertical number is the depth of the paint square remaining on the surface after a deep indentation of 10 mm.

BAD ORiGi ^ _AL 9098A6 / 0823 - 12 -

U9R915

Pressed, "" * * now 12.7 χ 7.3 whether large metal sheets which had been treated in the above-mentioned invented catfish were old for electrophoretical application and containing 12% solids per 100 g. r »en Laok electrophoretically painted. X) The lacquer application was carried out for two minutes at 60 ToIt. The Laokfil * obtained was then stored Hinuten 30 at 150 ⁰ C. The weight and the bead of the organic over-eye were measured. The Olana was also observed. Other sheets that had not been treated according to the process according to the invention were painted and rated in the same way, the results are shown in Table 3 below.

table 3

Sick Duration of the phosphate treatment
ment in Hin.
without Ütroean-jait St roman
turn | turn . anchor steel Weight of the orga
niche fiIne
Storage in g riladioke
in / ν 1 untreated b 0 O, 42G 12.7 2 2 0 0.385 9.2-12.7 3 4th 1 12.7 4th 2 2 0.553 19.3 5 2 1 0.577 22.9 6th 4th remediation 22.9 7th see Anne, 12.7

Note The metal sheets 7 were phosphated for 1 minute without the application of electricity, then treated for 1 minute at 1.1 A / dm ^{2 of} electricity and then treated for 1 minute without the application of electricity.

909846/0823

- 13 -

H 9 R 9 1 S - 13 -

Ss is traditional, since 8 on the according to the invention geaäfien Processed treated sheets 4, 5 and 6 heavier and thicker IT covers were obtained.

The dian «of the lacquer on sheets 1, 2, 3 and 7 was roughly the same, and on sheets 4, 5 and 6 it was also about the same, but §ρ $ Β · ν ala that on sheets 1, 2, 3 and 7

- ** ^t "***" »* ^ttel » TS09846 / 0823 -U-

Claims (9)

T496915-14 claims 1. Method sub application βin · β setalliechee containing zinc Zinkphoaphat Übersuges avf an iron surface, characterized by the fact that the surface does not appear without Stros application old of a converting zinc phosphate solution Is brought into contact, bia aich the tin phosphate uberasug is essentially completely formed, and the old surface provided with oversized surface is then formed in an oversized form Zinkphoephatlusuag ala cathode is switched, ao dafl zinc is deposited. 2. The method according to claim 1, characterized in that the surface is immersed or by spraying a zinc phosphate solution containing 5 to 90 g / l FO ₄ , 3 to 8 g / l free phosphoric acid and accelerator and then brought into contact in the same solution ala cathode is respected. 3. The method according to claim 1 and 2, characterized in that the surface is brought into contact with a zinc phosphate solution containing chlorine as a beach accelerator. 4. The method according to claim 1 bia 3 »gekennseichnet characterized in that the surface by dipping in, the coating-forming Solution is treated, wherein the workpiece is suspended from a support having an electrical line lat .9 09 8 46/0823 originally inspected - 15 - and the power is turned on when the zinc phosphate coating is essentially complete. 5. The method according to claim 1 to 3, characterized in that that the surface is guided through a Spritesone by means of a conveyor, in which it is filled with a zinc phoephate solution is sprayed until the zinc phosphate loosening is essentially is complete, and then brought into contact with an electrical line and the current is switched on, while the surface is immersed in the spray solution in a container 6. The method according to claim 1 to 3, characterized in that spray the surface with a Sinkphoaphat-18sung is brought into contact until the phosphate coating is essentially complete and then with an electrical one Electricity is connected. 7. Method according to claims 1 to 6, characterized in that the current density in the cathodic connection of the surface is less than 3.3 A / dm, preferably in the range of 0.5> 5 to 1.6i> A / dm ² . 8. The method according to .Anspruch 1 to 7, characterized in that the surface is treated ^{at temperatures of 21 to 71 0 U.} 9. The method according to claim 1 to 8, characterized in that dafl after de. Applying the gold. Zinc contains end t η 909 8-4 6/0823 ^ßAD O Zinkphoaphatütorsuf ·· medium · a ·· «l« ktroylior «ti« oh «a T · * - drive «« in £ aek is applied.