Chandrasekaran, V.

Gomathi, P.S.

Guruviah, S.

Narasimhan, K.C.

Udupa, H.V.K.

IR@CECRI

148273G<lVBRNJllSNrOF INDIA, 'rHB M"aaacnlc:c.214, AQIMa ....... H.f)$. R(N), CALC:U'l'TA-1'. ClDllp1eu Specif1ce~IOft •• 148273dfttecf 24th HcW'-.ber, 1978. J App11Ql~1on No.. N4.1oeV78clPttell 24~ NoVeMber, 19'18. Cbtv1c1ed out of aeo.1119/alJJ'6.erial ~.,14616.lif~"dated to 31'd .JUly, 1'717.AC:eeptazj:e of the ccmpl•• 8P8c:1f1cat1on actven:1.ees on 27tbDec:.aber %980.Index at acceptance -.International C1aaa1fication I C 01 b - 25/264.IMPROVED PROCISS Pal THB PRCDUC'l'ICIf or ZIlICPHCI!IPHA'l'B USI~ zIJIC CARBCMATB.0,:COUNCILLSCI&MTIPIC && IIl)US'l'RIAL RESEAROIRafi Maro, NewDelhi-l, India, an Indianreoi8tered body incorporated uncSertheReoistration of Soc:tKi~ Act (Act xxt ~ 1110)·The fol10W1D9 apecifloa\t1on particularly c5esc~ibe8 aDela.certain...t. na~ure of th.:i,EIinvention and the manner in vhJ.dt it 1. ~ beperEormed J-I+8:l,3'this i8 an invention by HANDADY VENKATAKRISHNAUDUPA, Director, KAPIS'fHALA.M CHETLUR NARA3IHHAt~, Scien.ttst,.SUBBIAH HADAR aURUVIAH, Scientist, VENKArASUBRAMANIAlfCHA~DRASEKARAN, Senior Scientific Assistant, Mra PADMAJfA.BASAJKARANARAYAHA GOMATHI J Junior Technioal Assistant, allot tbe Central Bleotrochemical Research Institute,Iarailcudi-623 006, Tamil Nadu, India, all India~iti •• ns.This invention relates to the improvements in orrelating to the production of zinc phosphate by doubledeoomposition of zinc carbonate with orthophosphoric acidtor use as anti-oorrosive primers.Hitherto it has been the practioe to prepare sinophosp:nate by tbe interaotion of sine sulphate with d1sodiUlllIQ'drogen phosphate to get zino phosphate, sodium sUlphateaDd sUlpburic i:liOid.The objection to the prooedure described above 1sthat ;i.t involves in the tormation ot sodium sulphate and.ulphl1ric aoid.. The presence of sulphate im.purity is notd•• lrable tor tb. applicatloll ot nne phosphate in aatl-oorro:;lve primers and unless proper precautions are takeala 'ha ~hing ot the ssaple the sulphate may contamina••'he P:~Odllot.The object ot ~his invention is to obviate thesed1aad.vantagea aJid to prepare zinc phosphate ot suitablepunt;' needed tor u•• as anti-eorrosive primer.Z1JlOoarbonate is made 1nto 15 to 25~ but preferably2~ .1ur17 Witt! water. This slurry is allowed to react vt..h'he .if.leMo.etrio quantity ot orthophosphorio aoid dilute4tro. :LI1 to 1.1 but preterab17 b.tween 1:3 and lt5 at' .. peratur .. rans*ac trom '0 to 600Cwith stirring.,1.,R73'this aix\ure is kept tor abou\ 12 to ~ hrs with stirring.The orystallised salt after deoantation of the 8uperaa'entliquor is washed twice or thrioe with fresh oold water,ihen onoe or twice with hot water, centrifuged and finallydried at 100 ~o 120°C tor 2 to 4 hours. This sample issubjeoted to the test as an anti-oorrosive primer.Accordingly the improved process for the prod\lotionof sinc phosphate by the interaction of zino oarbonate andorthophosphoric aoid is characterised in that the doubledecomposition reaotion is carried out by reaoting 15-2,.slurry of zinc carbonate with water a.nd stoichioaetric aaOUQ';of orthophosphor1c acid diluted from 1:1 and 1:7 at ate.perature range of 30 to 60° and isola.ting the solid z1nophosphate formed.The zinc phc,sphate 'prepared by this method vas sub-jeoted tor use a. anti-oorrosive primer. For this, zincphosphate prepared by the invented method \fIas mixed withtron oxide and this mixture was in,corporated in double boiled('il medium and linseed stand oil mediwn and ground well tofora a paint. After adjusting the consistency tbe pain\.~.r. ooated on pickled •••• panels and rusted •• s. panel.end sUbjeoted to corrosion tests both by salt spr., andexposing to the atmosphere preferably marine atmosphere atHandapaa. The results obtained with the zino phosphateprepared b7 this in'Yented .ethod was comparable with thezinc phosphate pigaent obtained trOll trade.The present invention consists of a prooess tor thep.roduotion at zino phosphate for use as a.nticorrosive primer,whioh comprises ot double decompositioD ot zino oarbonatev:l.th orthophospborio acid and isolating +-he 8.01i4 sinophosphaie, whereill 15 ,. 2~ bllt preferably 2OJ' slu1"!7 of.:~1lCoarbonate 18 aliowed to react ..,1_ 'Ute .lolctd ... tricquaatity of' or1thophospbor1c s.cid dilued tl'Ola lt1' to 1.1~4148.17-1.• , , ..e:f.r_i,¥ 1., aDd 115 ., ' .... ratv •• r-e1nc trOll~ to 60·C vitb .fficient .tirring and tinally o.ntr1~lns tb. solid slno phosphate with oold and hot water wash'e O.. t&:l.1lpure prod\lot and dmllB the .:aae. Tbe sincpllO.pha~epipent prepared b~ tbis .etbod proved to be~oaparabl. with that Ob~a1neclfroa tra4e wh.n .ub~eoted'0 oorrosion trials.linc plto_pbate prepared b~ thi •• ethod is pure8IIOUP for 1t. Wleia aati-oorroalve primer~typical ... ple.liDO oarbonate (20 g)Oribophosphorio acid'I_perature of _actioDY~eld of sino phosphate• • 2OJ' slurl7•• 1., dilution'5°C98"••••Purit71 lino content 95.4" •• Phosphate conten'"the following table slve •• 0" of the lZ"operti.s otIi no phll_phat•• upl.aProperti., of I1AO P'Rhat •.1.•Volatile -.tt.r (,,) •• 7.12.• Oil .sorptloa • • 21 g/lOOg ptp.n\,. Denaity sial •• ,..,4. pH of extract •• 5.85. Bxtraot inhibi ti veloorrosive •• Corrosiv.11110 phosphat. pr.pared b7 thi_ 1nv"10n .... 811.&_lIith 1rl)1lond. aad this II1zture was incorporated in doubleDOlledoil _cl11a and 11naeeelst&Del011 iaecl11a aa4 sroWllllIell to fol'll a paint. After ad~Wltlll8tbe OOulS'8D07,hepaints w.re coat_ on piokled •••• paD.l. and ruat •••••pallels to a thioklluS ot 20 '0 25'-. ~ ria•• ,...1. veN_b~eot.d '0 tbe "0.1 t.u· UJre salt .PIIllV t wilib ,.sed:1_ ob~ri" HiL_io., '._"" ill ,. oh1o ......solution'" s.-re1oa 1. cU.atU1ed·vat...1.8~:'73.·The painted paMla "ere upoaed 1ft triplicate a'~aD4ap&l11Camp. It va, obael'Ye4lat the end of aeven IIOnth.Ghat thu performanoe ot pr1laer paiDt alone was sll11lar to~h. performanoe ot sino phosphate primer obtained tro.~ra4.. However, the performanoe ot primer (developed),...ith flr.i8hing paint wa.sbetter than that of co_ercialJ.1rtaer with finishing pa.1nt.The following are the 1I&1nadvantages of this invention:a) Zine phosphate 1s obtained in pure form with good,1.elels. b) This zinc: phosphate pipent is comparable witht:le sino phosphate pigaent obtaiaed trom trade. e) The"'lrrosion resistant property of the zinc phosphate/redoxide primer is better tha.n zinc Chromate/red oxide pr1JlerOJ' IS 2074.The present invention consiat8 of a p~ocess fOr thepl'oduction of sine phosphate tor use in anti-eorroslvepr tmers Wi'ter-e1na slurry of sine carbonate is reacted vi thstoichiometric quantity ot orthoph6sphoric aeid taken indilution .ranging trom 111 to la7 but preferably between11Sand 1:: 5 at tempera.tures ranging trom ~O to 60°C with,ffioient stirring.Zinc phosphate pigment prepared by this aethod proyedto beOom~ara.ble with that obtained from trade When8ubjectedto cor~ion tria18"Ve olalm.1. An laproved prooess tor the prOduction ot zincpIl.(lspaaceI)y intarac1:io}t of sino carbonate and orthophoaphorio_11 ohar&.tJterised-i~ that the elouble-decomposit1oDreactionia 3arried out by reacti~ 15-2'" alurry of zinc oarbo~t.wi'n wat.r and .toiendo •• tria .-ount ot ortbopboapboric acielcliltLted trc'm111 to..117 ••. a t..... tur. ranp of )0 '0 6O·C.. *_t-** .. vith~irr1GS aaa,iIola'iac tbe soU. st.jIbospbate foraed.'48.1l732. The process as claimed in cL~.iIll1 wherein thodoub1e-decollposition reaction is oarried wi I;.hstirring -the reaction mixture for 12 to 30 hours and Grier;, "entri-taging the solid zinc phospha.te formed and ""rtsningthesame with cold and hot water to obtain a pure ~roduct.,. The process as claimed in claim 1 ~nd 2 where1nthe sinc carbonate slurry with water used is preferably ~.4. The process as olaimed in any of the proceedingolaims wherein the conoentration ot orthophosphoric aci4uaed is preferably between 1:3 and 115~5. The process a.s claiaed in olaims 1. and 2 whereinthe washings obtained atter oentrifuging solid zino pho8,phateformed are reused in the process to prepa.re zino carbona;;eslurry.6. An iaproved prooess tor the preparation of s1110phosphate by interaction of sino'carbonate and orlbophoa-phoric aoid subatantial17 as herein desoribed.Dat.d this 26th 487 of JUly, 1977.-6- PATENTS 0I'JICBRCSIS

Improved process for the production of zinc phosphate using zinc carbonate

Abstract

Similar works

Full text

Available Versions

IR@CECRI