CA1193804A - Leather tanning agent and process for making same - Google Patents

Abstract

LEATHER TANNING AGENT AND PROCESS FOR MAKING
SAME
A b s t r a c t A leather tanning agent characterized in that it con-tains the following components, per cent by weight:
sulphate of aluminium and ammonium containing 0.001 to 1.0% of TiO2 or TiO2 and ZrO2 3 to 20 and/or sulphate of zirconium and ammonium con-taining 0.001 to 0.5% of TiO2 or TiO2 and Al2O3 20 to 50 and sulphate of titanyl and ammonium contain-ing 0.001 to 1.0% of Al2O3 and/or ZrO2 the balance.

The above-mentioned additives of TiO2, ZrO2 and Al2O3 incorporated in the sulphates are present therein in a che-mically combined state.
A process for producing the leather tanning agent is c h a r a c t e r i z e d i n t h a t a titanium-con-taining solution with a concentration of titanium of from 80 to 200 g/l as calculated for titanium dioxide is reacted with a solution of aluminium sulphate containing 80 to 130 g/l of aluminium as calculated for alumina, and/or a so-lution of zirconium sulphate containing 50 to 200 g/l of zir-conium as calculated for zirconium dioxide in the presence of sulphuric acid and ammonium sulphate.
The sulphate tanning agent according to the present invention can be very useful in the leather industry.

Description

LEATF~'R TA~IN~ AGEN~ AND PROC~SS FO~
MAKI~G SA~

'~he present invention relates to the leather :indust ry and~ more speci~'ically~ to a leather -tanning agent and to a process .for [llaking same The prior ar-t tanning agents employed in the leather lndustry include chrome tanning agents and vegetable tann-ing agents comprising e:xtracts of oak, spruce, willow, ches-tnut, quebracho9 mimosa, and the like. Ho~vever, the use o~ c~-romium is harmful for t~e operating personnel3 it results in the erlvironment pollution, while the use of vegetable tanning ageLlts neces~itates a considerable rate o~' consumption of vegetable raw materials, -thus renderiag damages to the environments.
Known in -the art i9 a titanium tanning agent ~or hid-es compLisin~; a double sulphate o~ titanyl and ammonium in the monoh~dra-te ~orm (NHL~)2~iO($0~)2H~O ~cf. USSR Inven~
tor's Certificate No~ 2~4598, Cl.2$a published in 1969).
The use o~ ti-taniw~ tanning agent rules out the necessi-ty o~ using vegetable -tanning agents and considerably lowers the rate of consumption Oe chrome tauning agent~ ~itanium tanning agent makes it possible to efficiently carry out -the process o~ tanning hides, whereupon -the latter acquire improved characte:ristlcs, but the -temperature o~ tanLled pel-~ shrlnking does not reach the desired valueO
Also known in the art is a zirconiw~ leather tanning agent whic~l, as compared to -titanium -tanning agent, increas-es -t~e temperature of -tanned pelt shrinking (c1'. A.I. Me--telkin, NoI~ Kolesnikova, E.V. Kuz'rnina 'tZirconium '~anning"~
1972, "Legkaya Industriya" (Light ~ndus-tr~) Publishing Ho-use, ~loscow~ p. 220). ~Iowaver, zirconium tanning agent is more expensive -than t:itanium one.
A tannin~ at~ent is kno~n~ containing both titanium and zirconium the application of which results in an im-p~oved quality o~ leather (cl. USSR Inventor's Certifica-te NoO 340702, Cl.28a, 1972).
The proces~ for th~ manufacture o~ this ~tanning agent comprises -the s-teps of mixing two solu-tions a solution containing a sal-t o~ titanium and a solu-tion containing a salt of zirconium, whereafter the solutions ar~ evaporat-ad to dryness. This process involves higher inputs o~ powerO
'~he prese~lt invention is dlrected to the provision of such a leather tanning ~gent which would be superior to the prior art tanning a~ents (including titanium one) in its propertie~ and could ba produced by a simple process using readil~7 available reaRen-ts and mineral s-tock materi-als~
This object is acc~mplished b~ the provision o~ a lea-ther tanning agent incorporating sulphate of titanyl and ammonium, which, accordin~, to the presen-t inven-tion, is cha~
racteri~ed by that i-t con-tains the following components, per cent by weight:
sulpha-te of aluminium and ammonium con-taining OoOOl to 1.0% '~iO2 or '~iO2 and ZrO2 ~ to 20 $~J~

and/or sulp~ate o~ zirconium and am~o.lium contain-ing 0.001 to 0O5~o of ~iO2 or ~iO2 and A120~ 20 to 50 and sulphate of tltanyl and alllmoniurn containing 0.001 to 1.0% o~ A1203 and/or ZrO2 the bala~ce.
'I'he above-s-tated addi-tives of '~iO2, ZxO2 and A1203~
lncorporated in thè above-specified sulpha~es are presen-t therein in chemically combined state.
~ he tanni~ agent Qf such composition has the advan~t-age residing in that it erables an effective process of -tanning hides so as to impart hi~h physico-mechanical cha-racteristics thereto~
The terr~ t'sulphate of ammonium and aluminium" is used here to denote the compound o~ the formula ~II41~1(S0~)2 12 H209 which contains cheraically combined additives of ~i2 or ~iO2 and ZrO2.
'~e term "sulphate of zirconium and ammoniurn" is used here to deno-te the compound o~ the formula (NH~)2Zr2(0~I)5~(8~)2;5 ~ 2~ WhiCil contains chemically combined additives ol`'L'iO2 or 'i`iO2 and A1203.
The term "sulphate of titanyl and amr[lonium't is ~ed to denote -the cornpownd of the formula (NH~)2~iO(S04)2-H20, which contains chemically combined addi-tives o~ A1203 and/
or ZrO2~
~ he tanning agent of the invention is produced by a process which, according -to the present invention, compris .~9~

es reacting a solution con-taining 80 to 200 g/l o~ -tita~
nium as c~lcula-ted eor titanium dioxide with a solu-tion o_' a.Luminium sulphate containing 80 to 130 g/l o:~ alumi-nium as calculatecl for aluminiurn o~ide, and/or a solution of ziLconium sulpha-te containing 50 to 200 g~l of ziroonium a~ calculated ~or zirconium oxicle in the presence Oe sul-phuric acicl and anlmonium sulpha-te.
The process ~or producing the tanning~ agent accord-ing to the ~resent invention is advantageous in that it can be readily realized on a commercial scale 9 since the process i9 carried out un~er normal conditions: at room temperature and normal pressure with -the use Oe readily available and inexpensive reagents and mineral raw materi-als~
The ~ollo~ing embodiments of the composition o~ the sulphate tannin,~ agent are covered by the present invention9 deDending on the combination of the sulphates employed, namely 9 2-component an~ 3 component tanning agents.
A ti-tani~tm-aluminium tanning agen-t ha,s the ~ollowing composit.ion 9 per cent by we~igh-t:
sulpha-te oY aluminium and ammonium containing 0,001 -to l.n% o~ TiO~ 3 -to 20 sulph~-te O:e -titan~l and a~iimonium con-taining 0.001 to l~O~o 0:~ A120~ -the balanceO
This tanning agent mal~es it possible to increase the -temperat~e oY tanned pelt shrinking b~ 4-6C as compared ~o the ,orior art titanium -tannin~ agent.

~3~

A -titaniu~-zirconium tanning agen-t has the ~ol].owing composition, per cent by weight:
sulphate of zirconium and arnmonium con-taining 0,001 to 0~1% O:e T102 20 -to 50 sulpha-te OL' titanyl and ammoniu~ containing 0.001 to 00 l~o of ZrO2 the balance.
'~his tanning agen-t l~akes i-t possible to increase -the shrinking tempera-ture o~ pelt tanneA -therewith by 8-9C
as compared -to the prior art titanium tanning agent.
A titanium-~irconium-aluminium tanning agent has the ~ollo~in~ composition, per cent by weight:
sulphate of aluminium and a!~monium containing 0.001 to 1O05' of '~iO2 and ZrO2 ~ to 20 sulphate of zirconium and ammonium containing 0~001 to 0.5% of '~iO2 and A1203 20 to 50 sulphate o~ titanyl and a~nmonium containin~
0,001 -to l~O~o of A1~03 and ZrO2 -the balance.
This ta~ning agent makes it possible to increase the shrin~ing tempera-ture O:e pel-t tanned therewith by 10 12C
as compared to -the prior art titanium tanning agent~
The titanium-aluminium tanrling agent according to the present invention can include also 1 to 10% by weigkt of silicic acid which serves as a filler for leather ~and rnak-es it possible to increase their yield by weight and thick-ness after tanning by 0.~ -to 1.0% as compared to the prior art -titaniurn -tanning agent.
The choice of the content ran~es of the above-speci ~ 3.~3~
~6~

~ieà sulphates in the tannin~ agent according to -the pre sen-t inven-tlon is clic-tated by that in case the content o:~
sulphate of alutninium and arnmonium i5 less -than 3~0 by we-igh-t, no activation of the taLlning e~f'ec-t o~ titanyl and ar~mon:Lum sulphate i9 displayed by the tanning agent. An increase o:L' the con-tent o~ sulphate of aluminium and arnmo-nium above 20% by weigh-t causes a reduction O:e the content oI' the mairl tannin~ component, i.e. of sulpha-te of titanyl and ammonium, which results in loweri.n, of the tanni~g pro perties.
In case the content of sulphate of zirconium and am-monium in the tannin~ agent is less than 20% b~ weight its tanning e~I'ect is weakened? while wi.th the content o~ this component exceeding 50% by weight the tanning e~fect of ti-tanium is suppressed by zirconium and 9 moreover9 this adds to the cost o~ the tanning agen-t.
The choice of the content ranges of additives of L`iO2, ZrO2 A1203 chemically co~bined in sulpha-tes is dictat ed by -tha-t below 0.001~ by weight they do no-t display the e~ect o~ activa-tion of sulpha-tes in -tanning, whereas the upper limit o~ the ran~.,e is defined by the condi-tions of the process for the prod~ction of the tanning agent~
'~he ~ollowin~ embodiments of -the process for produc-in~ the tannin, agen-t according -to the presen-t invention are po9sible depending on the character o.~ -the -tanning agent to be producecl: ti-tanium-aluminium~ or titanium-zirconium, 3~

or ti lianium-zlrconium-a:Lurniniurn, Acco~ing t~ -~he present invention, ~he titanium-aluminium tanninp, a~-,ent is p~oduced b~ the process which resides in that a solution of sulphate of titanyl and am-monium containing 80 to 140 g/l of ti-tanium a5 calculated for titania is added wi-th ammonium sulphate and sulphuric aci(l till -the moment o~ the beginning of crystalliæation o:E sulpha-te of titanyl anc~ a:-lmonium, whereafter a solution of alualiniurn sulphate and additionally amtnonium sulphate and sulphuric acid are added during a period from 1 to 5 hours till -the -to-tal content of ~ree sulphuric acid and aluminium sulphatJe ln -the reaction solution becomes equal to 400-600 g/l and the molar ratio of alumini.um to tita-nium is equal to 0.03-0.24:1.
'~he titanium-aluminium tanning agent can also be pro-duced from a sulphuric acid solution containing 100 to 200 g/l o~ titanium as calculated for titania and ~00 to 520 ~/1 oP sulphur~c acidg ~his solution resul-ting from pro-cessing OI titanium-con-taining stock materials. 'I'o -this end, ammonium sulphate is added to this solu-tion, till the resultln~ sulpha-te of titanyl and ammonium begins to cry-stallize, wherea~ter a solution of aluminium sulphate and additionall~ ammonium sulphate are added till the con-tent of ~ree ammonium sulpha-te in the reaction solution becomes 210 -to 350 g/L and the molar :ratio of aluminium--to~ti-tanium, 0.03~0.~
'rhe use of the above-mentioned sulphuric aci.d solu -tion has the iollowin~ advantage~: (1) there i~ no need in speciaL .recover~ OL` -ti-tanyl and ammoniulll sulphate there ~rom, (2) the degree o:C precipitation of titanium from this sulpha-te solu-tion is higher than ~rom the solution o~ sul-phate of -ti-tanyl an(i a~i~monium, and (3) -the resu:Ltin~ pro-duc-t has hi~ner -tan~.ing proper-ties.
'~o enhance tanning charac-teristics o:f the titanium-aluminium tanning agent, -the process for producing -thereof is conduc-ted -with -the adcLition of 1 -to lO,~o by weight of si-licic acid or sodi.um sal-t thereof. ~ilicic acid incorpora-t-ed in the tanning agent composi~ion serves as a filler and increases the yield of leather both i~ weight aud thick-ness.
According to the present invention, the process for producing a titanium-zirconium tannine. agen-t comprises in-troduction into ~ zirconium-con-taining solution o~ ammonium sulphate and sulphuric acicL till the begirlnin~ oI crystal~
liza-tion of the ~orming sulphate of zirconium and ammonium, wL1ereafter d~Iing a period of from 1 to 5 hours a solùtion o~ sulphate of titanyl and ammonium is added containing 80 to 140 g/l of ti-tanium as calculated for -ti-tania, and ad ditionally ammonium sulphate and sulph~ic acid is also in-troduced till tLle total conten-t of` ~ree ammonium sulphate and sulph~ric acid in -t~e reac-tion solution becomes e~ual to 770~1,000 g/l and -the molar ratio of zirconium to -tita~
nium is equal to 0.10-0.65:1~
Described h.ereinbelow are -two embodiments of the pro-cess ~or p.roducing a -titanium-zirconium-alumi.nium tanning agent. In one embodimen-t a zirconium-containing solution i~ adcled wi-th ammoniurn sulphate and sulphuric acid till the moment of crysta:Lliza~ion o~ -the resulting sulpha-te o~
zirconium ancl ammoniuln, wherea~-ter d~ing a perio~d of from 1 to 5 ho~s it is added with a solution o~ ammonium tita-nyl containing 80 to 140 g/l of ti-tanium as calculated ~or titania, a solu-tion of aluminium sulphat~ and addi tionally with ammonium sulphate and sulphuric acid -till the total con-tent o~ free ammonium sulphate and sulphuric acid in the reaction solution becomes equal to 770-1,000 g/l and the molar ratio o~ aluminium and zirconium to ti-tanium is equal to 0.0~~0.24:0.10-0.6~
Another embodimen-t o~ the process for producing the titanium-zirconium-aluminium tanning agen-t comprises ad-dition in-to a zirconium-containing solution o~ a sulp~uric acid solution cortaining 100 to 200 g/l of ti-tanium based on titania and 300 to ~20 g~l o~ sulphuric acid obtained ~rom processing a ti-tanium-con-taining raw material ~or a period o:E ~rom 6 to 10 ho~rs, along with a solution o~ alu-minium sulphate and arnmonium sulphate till the contont o~
~ree ammonium sulphate in the reaction solution is 400 to 580 g/l and the molar ra-tio o~ aluminium and zirconium to ti-tanium is equal to 0O0~-0.2~:0.10-0~65:1, In all the embodimen-ts th~ process for producing a sulpha-te -tanning agent is e~ected at room temperature under normal pressure. ~he s-tarting raw ma-terials and reagents are readily available materials~

~ or -the preparati.on o~ a t.itanium~containing solution use is ma~e either of sulpha~e of -titanyl and ammonium ob~ ,~
-tained i~ro~l processing a titanium-containing raw ma-terial, or oE this raw mater:ial a:Eter treatment thereof' wi-th sulphu-ric acid. As said raw material use can be made o~ ilMeni-te con-centrate, sphene concentrate, leucoxe~e concentrate~ and other concentrates o~ -titanium minerals~ ';.
FOI~ -the prepara-tion o~' a zirconium-con-taining solu~
-tion use is made OL ~irconium sulphate obtained ~rom proces-sing a zirconium containing raw material~ for example, zir-con concentra-te.
~ or a better understanding oE -the presen-t invention some speci~ic examples illustrating the production o~ -the -tanning agent are given hereinbelow.
E~ample 1 500 g of sulphate of titanyl and ammonium are dis-solved in 1 litre o~ wa-ter to obtain a solution containing 100 ~1 o~ ti-tanium as calculated for its dioxide~
Into the resulting solu-tion amr~onium sulpha-te and sul-phuric acid are added till the beginning of crystallization o.E sulphate of tita~yl and ammonium, wherea~-ter durirlg 2 ilours there is added 0.04 1 o~' the solution o~ aluminium sulphate containing 113 g/l of aluminium as calcula-ted x~ox its oxide and addi-tionally aluminium sulphate and sulphuric acid till -the total content o~ ~ree sulphuric acid and am-monil1m sulphate in -the reac-tion solu-tion is 550 g/l and the --ll--molar ratio of alurninium -to ti-tanium ls equal to 0~05;1.
'l'he resulting preGipitate is separated ~rom the solution b~ f'iltration~
'~he ~i~al produc-t yield i5 5~0 ~ It contains 9 per cent by weight: 'riO2,18.2; A120~ 20 It consists o~ two sulpha-tes, per cent by weigh-t:
sulphate o~ alurnini~ and ammonium containing 0.5~ o:e TiO2 13 sulp~ate of titanyl and ammonium containing 0.5~0 o~' A120~ -the balance.
ExRMple 2 Use is made of 1 li-tre of a sulphuric acid solution obtained from processing a titanium-con-taining stock con--taining 160 g/l o~ titanium as c~lculated ~or its dio~ide and 400 g~l o~ sulphuric acid. Into this solution ammonium sulphate is added till the beginning o~ crystallization o~
t~e ~orming sulpha-te o~ titanyl and ammonium, wherea~ter during 8 hours it is added with 0.2 1 o~ a solution o~ alu-minium sul.phate containing 113 g/l o~ aluminium as calcu~
lated ~or alumina~ and additionally ammonium sulphate till the con-tent o~ free ammonium sulphate in the solu-tion be-comes equal to 300 g/l an~ -the molar ratio of aluminium to -titanium is 0.20:1. 'rhe precipita-te is separated from the solution by ~iltration.
'~he yield o~ the final product is 980 g. It contains, per cent by weight: 'l'iO2, 16.33 A1203, 2.05. It consists o~

-two sulphates, ~er cent by weight:
sulphate of aluminium and ammonium contairlin~ 0.6~ 'I`iO2 17.8 sulphate o~ -titanyl and ammonium containin~ 0.6% o~' A120~ the balance.
E~arnple 3 'rhe process is conducted as described in the ~ore-going Examples 1 and 2, e~ce?t that after the introduction of the cornponents silicic acid is added in -the amount of 3.8 g (in the experiment o~ Example 1) and 6.0 g (in the experimen-t o~ Example 2)~
In the ~inal product the weight ratio o~ silicic acid to -titaniu~ dioxide is 0~05 lo Example 4 0.5 litre of a solution of zirconium sulpha-te con taining 180 g/l of zirconium as calculated for its dioxide is added Witil sulphuric acid an~ ammonium sulpha-te till t~le total con-ten-t of free sulphuric acid and ammonium sulphato becomes equal to 770 gtl. ~his results in crystallization o~ the formed sulphate o~ zirconium and ammonium ~rom the solutionl Into the reaction solution during t~o hours there is ~dded 1 litre o~ a solution of sulphate o~ titanyl and ammo-nium containing 117 g/l o~ titanium as c'~lculated ~or its dioxi.de, and additionally ammonium sulphate and sulphuric acid to the total conten-t o~ ~ree sulphuric acid and ammo-3~

nium sulpha-te o~ ~20 g/l and -the rnolar ratio o~ zirconium to titarliUm o~ 0~:1. The suspensiotl is allowed to stand ~or 24 hours. '~he precipitate is separated ~ tration.
The product yield i~ 1~000 g. It contains? per cent by weight: TiO2, 11.0, ZrO2, 8.5. '~he product consists o~
two sulpha-tes, per cent by weight:
sulphate o~ zirconiurn and amr~onium con-taining 0.005~0 o~ TiO2 45 sulphate o~ ti-tanyl an~l ar~moniu~
containing ~5% P Zr2 the balance.
~xample 5 Use is made o~ 005 li-tre o~ a solu-tion o~ zirconium containing 180 g/l Oe zirconium as calculated :eor its dio-xideO During 8 hours the solution is added with 1 li-tre of a sulph~ric acicl solution ob-tained ~rom processing a ti~
tanium-containi~g raw ma-terial containing 160 g/l o~ ti-ta~
nium as calculated ~or its dioxide and 400 g/l of sulphuric acid, as weLl as ammonium sulphate till the co~ten-t of ~ree arnrninium sulphate inthe solu-tion is 500 ~/1 and the molar ratio of zirconium to titaniurr~ is 0.~5:1~ The suspension is allowed to stand ~or 35 hours. The precipi-tate is sepa-rated by ~iltration.
The yield o~ -the ~inal product is 1,200 g. I-t contains, per cent by weight~ TiO2, 12.9i ZrO2, 7.3, '~he product con-sis-ts o~ -two sulphates~ per cent by wei~ht:
sulphate of ~irconiu~n and ammonium containing 0.006~o 0~ ~rio2 35 sulphate of titanyl and arnmoniu~l containin~ 00006~ ~ Zr2 the bal~nce.
Exa~ple 6 Use is rnade o[ 0.5 litre o~ a solu-tion of zirconiurn sulphate con-tainin~ 180 g/l o~' zirconium as calculated ~or zir-conia. Sulphur-ic acid and aml,lonium sulpha-te are adaed to -t~.is solu-tion till the total content o~ ree a~nmonium sul-pha-te and sulphuric acid become.s equal to 770 g/l~ l`he ~orm-ed sulphate o:f ammonium and zirconium starts to crystalli~e out o~ the solutionO Into the reaction solution there are added durin~ l hour 1~5 litres of a solution of sulphate o~' titanyl and ammonium containing lO0 g/l o~ titanium as cal-cula-ted for ti-tania, 0.05 litre of a solution of aluminiurn sulphate containing ll~ g/l OI' alurninium as calculated for alumina 9 and addi-tlonally sulphuric acid and ammonium sul~
phate till the total content o~ ~ree sulphuric acid and ammonium sulphate in -the solution is 820 g/l and the molar ratio o~ aluminium and zirconium to titaniurn is rnade squal to 0.05:0.40~ he suspension is allowed to stand ~or 20 houIs. The p~ecipita-te is separated by fil-tration~
Tne yield o~ the ~inal product is 1,500 ~. It con-tains, per cent by weigh-t: 'T'iO2~ 9~5, ZrO2, 5~9; Al20~, 003O
The product consists o~ three sulphates, per cent by weight:
sulphate o~ aluminium and ammonium containing 0.5% o~ TiO2 and ZrO2 3 sulphate o~ zirconium and ammonium containing 0.2% o~ q`io2 and A120~ 45 sulphate of titarlyl and ammonium containin~' 0.4~ Oe A1203 and ZrO2 the balance.
~a~nple 7 Use is made Oe 005 litre o~' a solu-tion o~ zirconium sulphate containin~ 150 g/l o-~ zirconium as calculated for its dio~icle. Into this solution there are added during 8 hours 1~7 litxes o~ a sulphate solution obtained .~rom proce-ssing of a titanium~containinO raw materia~ con-taining 160 g/l o~ -titanium as calculated for its dio~ide and 400 g/
oi sulphuric acid~ 0~04 li~re o~ a solution o~ aluminium sulphate containing 113 g~l oi` aluminium as calcula-ted ~or its oxîcle, and ammonium sulphate till the content o~ ~ree arnmonium sulphate in the reaction solution is 500 g/l and the molar ra-tio o~ aluminium and zirconium to ti.-tanium is 0.18~0.20~ he suspension a~ter the addit:iorl o~ the re~
agents is allowed to stand for 40 hours. The precipita-te is se~ara-ted by filtration, The weiOht of the prec:ipita~e is 1,~5 g. It con-tairls~
per cent by wei~h-t: TiO2, 14.0, ZrO2, 4.3, A1203, 2~8~ ~he produc-t consists o~ three sulphates, per cent by weight~
sulphate o~ aluminium and arnmonium containing 0~5% of TiO~ and ~rO2 20 sulphate o~ zirconium and arnmonium containing 0~2% o~ '~iO2 a~d A1203 21 -16~
sulphate o~ titanyl and ammonium con-tainin~ ~6% o~ A1203 and ZrO2 th~ balance.
The process according to Examples 1 through 7 is per-~ormed un~er norma:L conditions, i.e. at room temperature and normal pressure.
Tanning propertie~ o~ tne products according -to -the shrin~ing temperature ot~ the pelt treated therewith (are g:iven in -the table hereinbelow).
Table Tanning properties o~ t~e products rranning agent Temperature of ta~ned pelt shrinking, C

Sulph~te ol titanyl and ammonium (prior art -titanium tanning agent) 85 'l'itanium~aluminium ~anning agent according to ~xample 1 89 rl'itanium-aluminium tanning agent according to ~xample 2 91 Titanium-aluminium~silicon -tanning agent according to Example 3 92 Titanium-zirconium tanning agent according to E~ample 4 93 Titanium-zirconium tanning agent according to ~xample 5 9 ~i-tanium zirconium-aluminium tanning ag~ent according to ~ample 6 9 Titanium-zirconium-aluminium tanning according to E~ample 7 97 ~17-~ rom the daba showinO the shrinking tempera-ture o~
pelt tanned ~,vi-th -the above-speci~ied tanning agents i-t fol lol,vs that-the tannîllg agent accor~in~ to the pre~ent invon-~tlon produced as describecl in Examples 1 -through 7 improves the quality oL leather as compared to the prior art -tita-ni~l tanning ap;ent~
The best characteris-tics as regards the tempera-ture of tanned pelt shrinking are at-tained in the case o~ the titanium-Y,irconium-aluminium taanin~ agen-t prodllced with -the use OI a sulphate solu-bion resulting ~rom processing a ti-tanium-containin~ raw material (Example 7).
~ nh~nced taL~ning characteristics o~ the tanning agent of the present invention as compared to those o~ the prior art tannin~ agents are due to tne use of a combination O:e sul.phates incorporating, as it has been already speci~ied h~reinbe~ore, additives o~ TiO2, ZrO2 and A12Q3.

Claims (15)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:-

1. A leather tanning agent containing the follow-ing components, in per cent by weight, selected from the group consisting of:
sulphate of aluminum and ammonium containing 0.001 to 1.0% of TiO2, or TiO2 and ZrO2..................3 to 20%, and/or sulphate of zirconium and ammonium containing 0.001 to 0.5% of TiO2 or TiO2 and Al2O3...................................20 to 50%, and mixtures thereof;
and sulphate of titanyl and ammonium containing 0.001 to 1.0% of Al2O3 or Al2O3 and ZrO2.......................... the balance.

2. The tanning agent of claim 1, wherein TiO2, ZrO2 and Al2O3 contained in the sulphates are present in a chemically combined state.

3. The tanning agent of claim 1, containing the following components, in per cent by weight:
sulphate of aluminum and ammonium containing 0.001 to 1.0% of TiO2..........3 to 20%
sulphate of titanyl and ammonium containing 0.001 to 1.0% of Al2O3........................................... the balance.

4. The tanning agent of claim 1, containing the following components, in per cent by weight:
sulphate of zirconium and ammonium containing 0.001 to 1.0% of TiO2..............................20 to 50%
sulphate of titanyl and ammonium containing 0.001 to 1.0% of ZrO2.........................the balance.

5. The tanning agent of claim 1, containing the following components, in per cent by weight:
sulphate of aluminum and ammonium containing 0.001 to 1.0% of TiO2 and ZrO2......................3 to 20%
sulphate of zirconium and ammonium containing 0.001 to 0.5% of TiO2 and Al2O3..................... 20 to 50%
sulphate of titanyl and ammonium containing 0.001 to 1.0% of Al2O3 and ZrO2......................the balance.

6. The tanning agent of claims 1 to 3, also containing 1 to 10% by weight of silicic acid.

7. A process for producing a leather tanning agent according to claim 1, comprising reacting a titanium solution containing 80 to 200 g/l of titanium, as calculated for its dioxide, with a solution of aluminum sulphate containing from 80 to 130 g/l of aluminum, as calculated for its oxide, and a solution of zirconium sulphate containing 50 to 200 g/l of zirconium, as calculated for its dioxide, in the pre-sence of sulphuric acid and ammonium sulphate.

8. A process for producing a leather tanning agent according to claims 2 to 4, comprising reacting a titanium solution containing 80 to 200 g/l of titanium, as calculated for its dioxide, with a solu-tion of aluminum sulphate containing from 80 to 130 g/l of aluminum, as calculated for its oxide, and a solution of zirconium sulphate containing 50 to 200 g/l of zirconium, as calculated for its dioxide, in the presence of sulphuric acid and ammonium sulphate.

9. The process of claim 7, wherein the titanium solution is sulphate of titanyl and ammonium containing from 80 to 140 g/l of titanium, as calculated for its dioxide, which is added to ammonium sulphate and sul-phuric acid until crystallization of the sulphate of titanyl and ammonium begins, thereafter adding a solu-tion of sulphate of ammonium and sulphuric acid for 1 to 5 hours, to obtain a total content of free sul-phuric acid and ammonium sulphate of 400 to 600 g/l, and a molar ratio of aluminum to titanium of 0.03-0.24:1.

10. The process according to claim 7, wherein the titanium solution is a sulphate solution obtained from processing a titanium raw material containing 100 to 200 g/l of titanium, as calculated for its dioxide, and 300 to 520 g/l of sulphuric acid, said titanium solution being added to ammonium sulphate until crystallization of the formed sulphate of titanyl and ammonium begins, thereafter adding a solution of aluminum sulphate along with an additional amount of ammonium sulphate for a period of from 6 to 10 hours to obtain a free ammonium sulphate content in the reaction solution of 210 to 350 g/l and a molar ratio of aluminum to titanium of 0.03-0.24:1.

11. A process according to claims 9 or 10, wherein silicic acid or its sodium salt is added to obtain a molar ratio of silicon to titanium of 0.007-0.70:1.

12. The process of claim 7, wherein ammonium sulphate and sulphuric acid are added to said zirconium-containing solution until crystallization of the formed sulphate of zirconium and ammonium begins, thereafter adding a solution of sulphate of titanyl and ammonium containing 80 to 140 g/l of titanium, as calculated for its dioxide, for 1 to 5 hours, and adding ammonium sul-phate and sulphuric acid until obtaining a total content of free ammonium sulphate and sulphuric acid in the re-action solution of from 770 to 1,000 g/l and a molar ratio of zirconium to titanium of 0.10-0.65:1.

13. The process of claim 12, wherein after the crystallization of the sulphate of ammonium and zir-conium begins, a solution of aluminum sulphate is added thereto until obtaining a molar ratio of aluminum and zirconium to titanium in the solution equal to 0.03-0.24:0.10-0.65:1, respectively.

14. The process according to claim 7, wherein a sulphate solution is added to the zirconium-containing solution for a period of from 6 to 10 hours; said sul-phate solution obtained from the processing of a titanium raw material containing 100 to 200 g/1 of titanium, as calculated for its dioxide, and 300 to 520 g/l of sul-phuric acid and ammonium sulphate, until obtaining a content of free ammonium sulphate in the reaction solu-tion of from 400 to 580 g/l and a molar ratio of zir-conium to titanium of 0.10-0.65:1.

15. The process of claim 14, wherein a solution of aluminum sulphate is added to the reaction solution to obtain a molar ratio of aluminum and zirconium to titanium in the solution of 0.03-0.24:0.10-0.65:1, respectively.