Title of Invention

"A PROCESS FOR THE PREPARATION OF NOVEL ORGANO-METTALIC POLYMERIC MATRIX USEFUL AS TANNING AGENT"

Abstract A process for the preparation of novel organo-metallic polymeric matrix useful as tanning agent. In the process of present invention an aromatic hydrocarbon is sulphonated using sulphuric acid. Conventional masking agent is added, which is then treated with formaldehyde at a temperature range of 45 -70°C over a period of 20 -40 min. 0.5 - 2% w/v, of urea - formaldehyde adduct is condensed with the above mass at 45 - 70°C for a period of 20 - 60min. 0.5 - 10 moles of complex forming agent per mole of the aromatic hydrocarbon is then added to the condensate, which is treated with a metal salt. The reaction is continued for 1 - 5 hrs. The resulting reaction mixture is filtered and the final slurry is dried get the organo- metallic polymeric matrix.
Full Text reported by Schade et al (The Leather Manufacturer, p-11, July 1991) to be better compared to the phenol based systems for resisting discolouration of leather. But the major limitation associated with this type of syntan is the inadequate filling characteristics due to low molecular weights.
Equi-molar quantities of urea and formaldehyde under favourable conditions give thermosetting type of resins. These resins loose their aqueous solubility when molecular weight is raised to 500 - 600 Daltons. Urea can also cross link with methylol compounds to give rise to carbamide linkages resulting in light fast syntans.
The poor uptake of chromium in tanning has resulted in wide scale ecological concerns and economic loss. Chromium exhaustion can be improved by external exhaust aids based on long chain aliphatic dicarboxylates and aromatic polycarboxylates. But they not only require long tanning periods but also suffer from disadvantages of non-uniform distribution of chromium and difficulties in dyeing.
Aluminium(lll) being a d° metal does not enjoy ligand field stablisation advantages of d3 system like Cr(lll). Under proper ligating conditions and by proper manipulations of the Highest Occupied Molecular Orbital - Lowest Unoccupied Molecular Orbital (HOMO-LUMO) energy gaps, Al(lll) can be made to behave like pseudo transitional metal. This is best possible with the use of hydroxy acids as ligating agents. Despite being transition metals, Ti(IV) and Zr(IV) are d° systems. Proper ligation is the key to the use of these metal
ions in tanning. Zirconium(IV) is often not used as solo tannages, partly because of its indifferent effectiveness at raising the shrinkage temperature and partly because of the acidity of the salts. The vulnerability to hydrolysis of Zr-salt has meant that they must be applied at high concentration and at pH There have been several reports on the use of sulphate salts of aluminium, zirconium and titanium in tanning. In 1907 Garelli (Journal of Society of Leather Technologists and Chemists, 42, 351, 1958) reported the use of zirconium in tanning. Sommerville reported the preparation of a 50% basic zirconyl sulphate corresponding to Zr(OH)2SO4 (Journal of Society of Leather Technologists and Chemists, 38, 347,1954). Somerville later on patented (US Patent No 1,940,610) in 1941 a basic salt approximating to Zr(H)2SO4.Na2SO4, which was reported to be an effective tanning agent and was then commercially available as Zircotan N. Ranganathan and Reed (Journal of Society of Leather Technologists and Chemists, 42, 59, 1958) reported that the addition of acetic, lactic, formic, sulphanilic and gluconic acids helped in sufficiently masking zirconium. Hans et ak(US Patent No US4049379) patented complex salts having zirconium and aluminium as central atoms and oxo, hyd/oxy organic acids and sulphate ligands. Max (US
Patent No US 3953163) and Alain et al (US Patent No US5264000) reported the use of arylsulphones and lithium salts and ethylenediaminetetraacetic
acid as complexing agents for zirconium. Alain(US Patent No US 48306212% reported that aqueous compositions of sulphonated phenols, amines and metal (zirconium, aluminium, chromium and iron) could be used in tanning. Richard patented (US Patent No US 3966902)) polymeric complexes containing a monomer, metal ion, hydrophilic functional groups like hydroxyl, carboxyl or amino groups for using as tanning agents.
Though many products based on metal ions like chromium, aluminium, titanium, zirconium and iron have been reported, they lack the ability to withstand pH conditions of above 5.5 as described by Prof E Heidemann(Fundamentals of Leather Manufacture, Chapter 11, Eduard Roether KG publications 1st edition, 1993). Further when white/pastel shades are needed, phenolic compounds need be avoided to prevent discolouration. When any metal ion is discharged into the environment in large quantities, it generates great ecological concerns and hence the tanning agents need to have an active ingredient which could give near zero wastage of the metal salt.
The main objective of the present invention is to provide a process for the preparation of novel organo-metallic polymeric matrix for industrial applications, which obviates the drawbacks stated above.
Another objective of the present invention is to exploit the charge transfer interaction between the metal ion and various organic ligands capable of
having charge transfer interactions with the metal ion, thus enabling the reduction of HOMO-LUMO gap and reducing the lability of the metal-ligand bond.
Yet another objective of the present invention is to develop organo-metallic polymeric matrix which, when used in tanning, would resist discolouration of leather on ageing.
Still another objective of the present invention is to develop an organo-metallic polymeric matrix which resists precipitation of metal ion above pH value of 5.5.
Yet another objective of the present invention is to develop a product which when used in tanning gives an exhaustion of more than 95% of the metal salt employed.
Still another objective of the present invention is to provide novel organo-metallic polymeric matrix for industrial applications, particularly in tanning industry.
Accordingly the present invention provides a process for the preparation of novel organo-metallic polymeric matrix useful as tanning agent, which comprises i) sulphonating an aromatic hydrocarbon, preferably naphthalene,
anthraxcene, at 110 - 180°C for 1 - 3 hrs in conventional way,
wherein the amount of sulphuric acid used for sulphonation is 3 - 5
moles per mole of the aromatic hydrocarbon,
The present invention relates to a process for the preparation of novel organo metallic polymeric matrix useful as tanning agent. This matrix has potential use particularly as a self-tanning as well as a retanning agent for leather processing in tanning industry.
Conventional chrome tanning practices lack adequate filling of leather and give rise to an uptake of 50 - 60% of chromium offered. For providing filling action synthetic tanning agents (syntans) are used. The conventional syntans, hitherto known, are mostly anionic in nature and are usually derived from sulphonated phenols and other aromatic compounds. As reported by Prof. S.S. Dutta (Principles of Leather Manufacture, Chapter 10, ILTA publication, 3rd. edition, 1985), the first syntan was prepared by Stiasny by condensing phenol/cresol sulphonic acid with formaldehyde and later the Novolac type of syntan was prepared by sulphonating the condensed product of unsulphonated phenol/cresol and formaldehyde. The molecular weights of these syntans can be suitably adjusted by adduct formation. Gunther et al (US Patent No US 432 5890) and Albert et al (US Patent No US 400 0996) observed adequate filling in retanning of leather by using phenol - formaldehyde and phenol - sulphonic acid - urea formaldehyde condensates respectively . Kanthimathi et al ( Leather Science, 32/(3), 59, 1985) reported that photo- oxidation of phenolic constituents leading to discolouration of leather and poorer uptake of anionic dyes are some to the associated demerits of such products . Naphthalene sulphonic acid systems have been
ii) adding organic ligand such as herein defined, to the mixture as formed in step (i), at 40 - 60°C, wherein the amount of organic ligand used is 0.1-10 moles per mole of the aromatic hydrocarbon,
iii) treating the reaction mixture, as formed either in step (i) and (ii), with A2
formaldehyde at 45 - 70°C over a period of 20 - 40 min, iv) condensing the reaction mixture, as formed in step (iii), with a water
Compmising urea and formaldehyde at ratio (:) at 45 - 70°C for a period of 20-60 min,
v) complexing the condensate, as formed in step (iv) with organic ligand
and a metal salt as described herein, at a temperature in the range of
50 - 95°C, for a period of 1 - 5 hrs, vi) neutralizing the reaction mixture by known method to pH 2 - 4 at 30 -
50°C, vii) drying the filtrate of the reaction mixture, as formed in step (vi), by
known method for 3-60 sec at a temperature in the range of 130-
260°C to get novel organo-metallic polymeric matix.
In an embodiment of the present invention, the aromatic hydrocarbon used may be such as naphthalene, anthracene.
In another embodiment of the present invention, the amount of sulphuric acid used for sulphontion may be 3-5 moles per mole of the aromatic hydrocarbon.
In yet another embodiment of the present invention, the organic lignad used may be such as citric acid, phthalic acid, tartaric acid, salicylic acid,
oxalic acid, any alkali metal salt of these acids, either individually or in combination.
In still another embodiment of the present invention, the amount of organic ligand used maybe 0.1-10 moles per mole of the aromatic hydrocarbon.
In yet another embodiment of the present invention, the molar ratio of urea and formaldehyde for preparing the water-soluble adduct maybe maximum 1:1.
In still another embodiment of the present invention, the molecular weight of the water-soluble adduct may be in the range of 500 to2000 Daltons.
In yet another embodiment of the present invention, pH of the water-soluble adduct may be in the range of 3 to 6.
In still another embodiment of the present invention, the metal used for anchoring to the organic polymeric matrix may be such as zirconium, titanium, iron, aluminium, chromium.
In yet another embodiment of the present invention, the salt of the metal may be in the form such as sulphate, chloride, oxychloride either individually or in combination.
In still another embodiment of the present invention, the amount of metal salt used may be 2-10 moles per mole of the aromatic hydrocarbon.
Accordingly the present invention provides novel organo-metallic polymeric matrix prepared by the process described above.
An aromatic hydrocarbon is sulphonated using sulphuric acid at a molar ratio ranging from 1:3 to 1:5 over a period of 1-3 hrs at a temperature in the range of 110-180° C. Conventional masking agent, calculated as 0.1-0.4 mole per mole of the aromatic hydrocarbon is added as an optional step at 40-60°C to the reaction mixture, which is then treated with formaldehyde amounting maximum to a molar ratio of 1:1 with respect to the aromatic hydrocarbon at a temperature range of 45-70° C over a period of 20-40 min.
0.5- 2% w/v, of Urea - formaldehyde adduct of molecular weight in the range of 500 to 2000 Daltons, prepared separately by a conventional method using urea and formaldehyde in a molar ratio of maximum 1:1, is condensed with the above mass at45-70°C for a period of 20-60 min.
0.5-10 moles of complex forming agent per mole of the aromatic hydrocarbon is then added to the condensate, which is treated with a metal salt calculated as 1:2 to 1:10 in terms of molar ratio based on the moles of aromatic hydrocarbon used The reaction is continued for 1-5 hrs at a temperature in the range of 50-95° C.
The reaction mixture is then cooled to a temperature of 30-50°C and the pH is adjusted in the range of 2.0-4.0 by known method.
The resulting reaction mixture is filtered in a conventional way and the final slurry is dried by known method for 3-60 sec at a temperature in the range of 130-260°C.
The novelty of the present invention lies in selecting the starting material and in providing a process to prepare an organic polymeric matrix with ligating sites capable of anchoring metal ion, thereby forming a complex organo-metallic polymeric matrix , which is, unlike the conventional tanning/retanning agents, resistant to precipitation upto a much higher pH value of 10, facilitating higher neutralisation during the post tanning operation in leather processing.
The invention is described in detail in the following examples, which are provided by way of illustration only and therefore should not be construed to limit the scope of the invention.
Example I
63.2 gms of naphthalene was sulphonated with 146.4 gms of 98% sulphuric acid in a round bottom flask fitted with a stirrer at 120°C for 2 hrs. The sulphonated mass was transferred to a glass lined reaction vessel fitted with a stirrer and the mass was cooled down to 50°C.
A mixture of 103.5 gms of citric acid and 16.9 gms of phthalic acid was added to the above mass with continuous stirring. 12.8 ml formaldehyde was added drop by drop keeping the temperature at 55-60°C using a thermostatic water bath for 30 min.
14.8 gms urea was dissolved in 7.4 ml of formaldehyde at a pH of 5.5 with
vigorous stirring. The urea-formaldehyde adduct thus obtained was added to
the reaction mixture and the reaction was allowed to continue for 40 min.
16.8 gms of phthalic acid, 7 gms of sodium salicylate, 12.9 gms of sodium
citrate were then added to the reaction mixture along with 500 gms of
zirconium sulphate. Temperature was raised to 70°C and the condensation
was continued for another 1 hour. The temperature was then raised to 80°C
and the reaction was continued for another 1 hour.
Sulphosalicylic acid, pre-prepared by mixing 14 gms of salicylic acid with 14 ml of cone, sulphuric acid was added to the reaction mass and the heating was continued for 40 min. At this stage, 1 ml of the condensate was poured in 10 ml of water and was found to form a clear solution.
The reaction mass was then cooled to 30°C and was neutralised with 300 gms of sodium sulphite. The resulting mass was filtered and the filtrate was drum dried at 130°C. The resulting powder was packed in jute bag. A 1:10 solution of the product in water exhibited precipitation at a pH of 10.
This powder was used for the tanning of delimed goat skins and resulted in the production of white fuller leathers with a shrinkage temperature of 97±2°C, exhibiting an exhaustion of 94% of zirconium offered. The leathers had a smooth surface with minimised drawn grain as against those of conventional zirconium tanned leathers.
Example II
256.0 gms of naphthalene was sulphonated with 784.0 gms of 98% sulphuric acid in a round bottom flask fitted with a stirrer at 180°C for 1 hr. The sulphonated mass was transferred to a glass lined reaction vessel fitted with a stirrer and the mass was cooled down to 55°C.
40.0 ml formaldehyde was added drop by drop keeping the temperature at 65-70°C using a thermostatic water bath for 20 min. 59.4 gms urea was dissolved in 30.2 ml of formaldehyde at a pH of 3.5. The urea-formaldehyde adduct thus obtained was added to the reaction mixture and the reaction was allowed to continue for 60 min. 23.2 gms of phthalic acid, 15.8 gms of citric acid, 9.5 gms of oxalic acid, 6.4 gms of sodium salicylate, 11.8 gms of sodium citrate were added to the reactor along with 1500 gms of zirconium sulphate. Temperature was raised to 75°C and the condensation was continued for another 1 hr and 30 mins. The temperature was then raised to 80°C and the complexation was continued for another 1 hour. Sulphosalicylic acid, pre-prepared by mixing 14 gms of salicylic acid with 28 ml of cone, sulphuric acid was added to the reaction mass and the heating was continued for 40 min. At this stage, 1 ml of the condensate was poured in 10 ml of water and was found to form a clear solution.
The reaction mass was cooled to 30°C and was neutralised with 3075 gms of sodium sulphite. The resulting mass was filtered and the filtrate was spray dried at 260°C with contact time of 3 sec. The resulting powder was packed in jute bag. A 1:10 solution of the product in water exhibited precipitation at a pH of 7.0.
This powder was used for the tanning of pickled goat skins and resulted in the production of white fuller leathers with a shrinkage temperature of 97±2°C, exhibiting an exhaustion of 95.5% of zirconium offered. The leathers had a smooth and silky grain as against drawn grain of conventional zirconium tanned leathers.
Example III
78.3 gms of anthracene was sulphonated with 215.6 gms of 98% sulphuric acid in a round bottom flask fitted with a stirrer at 140°C for 3 hrs. The sulphonated mass was transferred to a glass lined reaction vessel fitted with a stirrer and the mass was cooled down to 50°C.
9.0 gms of tartaric acid was added to the above mass with continuous stirring. 5.0 ml formaldehyde was added drop by drop keeping the temperature at 45-50°C using a thermostatic water bath for 40 min. 14.8 gms urea was dissolved in 7.4 ml of formaldehyde at a pH of 6.0. The urea-formaldehyde adduct thus obtained was added to the reaction mixture and
the reaction was allowed to continue for 60 min. 9.6 gms of phthalic acid, 27.72 gms of oxalic acid, 6.4 gms of sodium salicylate, 12.9 gms of sodium citrate were added to the reactor along with 500 gms of zirconium sulphate. Temperature was raised to 50°C and the condensation was continued for another 30 min. The temperature was then raised to 60°C and the complexation was continued for another 30 min. Sulphosalicylic acid, pre-prepared by mixing 121 gms of salicylic acid with 45 ml of cone, sulphuric acid was added to the reaction mass and the heating was continued for 40 min. At this stage, 1 ml of the condensate was poured in 10 ml of water and was found to form a clear solution. The reaction mass was cooled to 30°C and was neutralised with 240 gms of sodium sulphite. The resulting mass was filtered and the filtrate was drum dried at 140°C. The resulting powder was packed in jute bag. A 1:10 solution of the product in water exhibited precipitation at a pH of 7.3.
This powder was used for the retanning of wet blue goat skins and resulted in the production of fuller leathers, exhibiting an exhaustion of 98% of zirconium offered. These retanned skins were dyed to rich yellow shades. The resulting leathers had a smooth and silky grain.
Example IV
52.2 gms of naphthalene was sulphonated with 172.5 gms of 98% sulphuric acid in a round bottom flask fitted with a stirrer at 130°C for 2 hrs 30 mins. The sulphonated mass was transferred to a glass lined reaction vessel fitted with a stirrer and the mass was cooled down to 50°C.
66.4 gms of phthalic acid was added to the above mass with continuous stirring. 13.8 ml formaldehyde was added drop by drop keeping the temperature at 55-60°C using a thermostatic water bath for 30 min. 13.2 gms urea was dissolved in 6.2 ml of formaldehyde at a pH of 4.5. The urea-formaldehyde adduct thus obtained was added to the reaction mixture and the reaction was allowed to continue for 60 min. 66.4 gms of phthalic acid, 110 gms of tartaric acid, 103.0 gms of citric acid were added to the reactor along with 350 gms of zirconium sulphate. The temperature was maintained at 65°C and condensation was continued for 1 hour. 148 gms of sodium salicylate and 88.2 gms of sodium citrate were added to the reactor along with 710 gms of zirconium sulphate. Temperature was raised to 75°C and the condensation was continued for another 2 hours. The temperature was then raised to 90°C and the complexation was continued for another 1 hours. Sulphosalicylic acid, pre-prepared by mixing 96 gms of salicylic acid with 76 ml of cone, sulphuric acid was added to the reaction mass and the heating was continued for 1 hour. At this stage, 1 ml of the condensate was poured in 10 ml of water and was found to form a clear solution. The reaction mass
was cooled to 30°C and was neutralised with 1080 gms of sodium sulphite. The resulting mass was filtered and the filtrate was drum dried at 135°C. The resulting powder was packed in jute bag. A 1:10 solution of the product in water exhibited precipitation at a pH of 7.0.
This powder was used for the tanning of pickled goat skins and resulted in the production of white fuller leathers with a shrinkage temperature of 94±2°C, exhibiting an exhaustion of 94.5% of zirconium offered. Unlike the conventional zirconium tanned leathers, which exhibit drawn grain appearance, these leathers were absolutely free from drawn grain.
Example V
56.3 gms of naphthalene was sulphonated with 131.4 gms of 98% sulphuric acid in a round bottom flask fitted with a stirrer at 120°C for 2 hrs. The sulphonated mass was transferred to a glass lined reaction vessel fitted with a stirrer and the mass was cooled down to 60°C.
9.96 gms of oxalic acid was added to the above mass with continuous stirring. 4.8 ml formaldehyde was added drop by drop keeping the
temperature at 55-60°C using a thermostatic water bath for 15 min. 13.2
gms urea was dissolved in 6.2 ml of formaldehyde at a pH of 5.5. The urea-formaldehyde adduct thus obtained was added to the reaction mixture and
the reaction was allowed to continue for 60 min. 9.96 gms of phthalic acid, 9.24 gms of citric acid were added to the reactor along with 240 gms of zirconium oxychloride. The temperature was maintained at 65°C and condensation was continued for 40 mins. 6.4 gms of sodium salicylate and 11.8 gms of sodium citrate were added to the reactor along with 470 gms of zirconium oxychloride. Temperature was raised to 70°C and the condensation was continued for another 1 hour. The temperature was then raised to 80°C and the complexation was continued for another 1 hour. Sulphosalicylic acid, pre-prepared by mixing 14 gms of salicylic acid with 14 ml of cone, sulphuric acid was added to the reaction mass and the heating was continued for 40 min. At this stage, 1 ml of the condensate was poured in 10 ml of water and was found to form a clear solution. The reaction mass was cooled to 30°C and was neutralised with 400 gms of sodium sulphite. The resulting mass was filtered and the filtrate was spray dried at 200°C with contact time of 4 sec. The resulting powder was packed in jute bag. A 1:10 solution of the product in water exhibited precipitation at a pH of 8.0.
This powder was used for the tanning of pickled goat skins and resulted in the production of white fuller leathers with a shrinkage temperature of 94±2°C, exhibiting an exhaustion of 94.5% of zirconium offered. The leathers were fuller and had a soft feel as against conventional zirconium tanned leathers.
Example VI
56.3 gms of naphthalene was sulphonated with 131.4 gms of 98% sulphuric acid in a round bottom flask fitted with a stirrer at 120°C for 2 hrs. The sulphonated mass was transferred to a glass lined reaction vessel fitted with a stirrer and the mass was cooled down to 60°C.
4.8 ml formaldehyde was added drop by drop keeping the temperature at 55-60°C using a thermostatic water bath for 15 min. 13.2 gms urea was dissolved in 6.2 ml of formaldehyde at a pH of 5.5. The urea-formaldehyde adduct thus obtained was added to the reaction mixture and the reaction was allowed to continue for 60 min. 2.96 gms of phthalic acid, 14.2 gms of citric acid were added to the reactor along with 247 gms of aluminium sulphate. The temperature was maintained at 65°C and condensation was continued for 40 mins. 3.4 gms of sodium salicylate and 5.9 gms of sodium citrate were added to the reactor along with 486 gms of aluminium sulphate. Temperature was raised to 70°C and the condensation was, continued for another 1 hour. The temperature was then raised to 90°C and the complexation was continued for another 1 hour. Sulphosalicylic acid, pre-prepared by mixing 1.4 gms of salicylic acid with 1.1 ml of cone, sulphuric acid was added to the reaction mass and the heating was continued for 40 min. At this stage, 1 ml of the condensate was poured in 10 ml of water and was found to form a
clear solution. The reaction mass was cooled to 30°C and was neutralised with 200 gms of sodium sulphite. The resulting mass was filtered and the filtrate was drum dried at 140°C. The resulting powder was packed in jute bag. A 1:10 solution of the product in water exhibited precipitation at a pH of 8.0.
This powder was used for the tanning of pickled goat skins and resulted in the production of white fuller leathers with a shrinkage temperature of 87±2°C, exhibiting an exhaustion of 98 % of aluminium offered. The leathers were fuller and enabled dyeing to rich shades.
Example VII
56.3 gms of naphthalene was sulphonated with 131.4 gms of 98% sulphuric acid in a round bottom flask fitted with a stirrer at 120°C for 2 hrs. The sulphonated mass was transferred to a glass lined reaction vessel fitted with a stirrer and the mass was cooled down to 60°C.
9.96 gms of phthalic acid was added to the above mass with continuous stirring. 4.8 ml formaldehyde was added drop by drop keeping the temperature at 55-60°C using a thermostatic water bath for 15 min. 13.2 gms urea was dissolved in 6.2 ml of formaldehyde at a pH of 5.5. The urea-formaldehyde adduct thus obtained was added to the reaction mixture and
the reaction was allowed to continue for 60 rnin. 9.96 gms of phthalic acid, 46.2 gms of citric acid, 6.4 gms of sodium salicylate and 11.8 gms of sodium citrate were added to the reactor along with 415 gms of titanium tetrachloride. Temperature was slowly raised to 70°C and the condensation was continued for another 1 hour. The temperature was then raised to 80°C and the complexation was continued for another 1 hour. Sulphosalicylic acid, pre-prepared by mixing 14 gms of salicylic acid with 14 ml of cone, sulphuric acid was added to the reaction mass and the heating was continued for 40 min. At this stage, 1 ml of the condensate was poured in 10 ml of water and was found to form a clear solution. The reaction mass was cooled to 30°C and was neutralised with 400 gms of sodium sulphite. The resulting mass was filtered and the filtrate was spray dried at 210°C with contact time of 4 sec. The resulting powder was packed in jute bag. A 1:10 solution of the product in water exhibited precipitation at a pH of 6.8.
This powder was used for the tanning of pickled goat skins and resulted in the production of white fuller leathers with a shrinkage temperature of 89±2°C, exhibiting an exhaustion of 93% of titanium offered.
Example VIII
56.3 gms of naphthalene was sulphonated with 131.4 gms of 98% sulphuric acid in a round bottom flask fitted with a stirrer at 120°C for 2 hrs. The sulphonated mass was transferred to a glass lined reaction vessel fitted with a stirrer and the mass was cooled down to 60°C.
9.96 gms of phthalic acid was added to the above mass with continuous stirring. 4.8 ml formaldehyde was added drop by drop keeping the temperature at 55-60°C using a thermostatic water bath for 15 min. 13.2 gms urea was dissolved in 6.2 ml of formaldehyde at a pH of 5.5. The urea-formaldehyde adduct thus obtained was added to the reaction mixture and the reaction was allowed to continue for 60 min. 365 gms of phthalic acid, 46.2 gms of citric acid were added to the reactor along with 489 gms of chromium sulphate. The temperature was maintained at 65°C and condensation was continued for 40 mins. 148 gms of sodium salicylate and 88.2 gms of sodium citrate were added to the reactor along with 978.0 gms of chromium sulphate. Temperature was raised to 70°C and the condensation was continued for another 1 hour. The temperature was then raised to 80°C and the compiexation was continued for another 1 hour. Sulphosalicylic acid, pre-prepared by mixing 96 gms of salicylic acid with 36 ml of cone, sulphuric acid was added to the reaction mass and the heating was continued for 40
min. At this stage, 1 ml of the condensate was poured in 10 ml of water and was found to form a clear solution. The reaction mass was cooled to 30°C and was neutralised with 400 gms of sodium sulphite. The resulting mass was filtered and the filtrate was drum dried at 130°C. The resulting product was packed in jute bag. A 1:10 solution of the product in water exhibited precipitation at a pH of 7.5.
This powder was used for the tanning of pickled goat skins and resulted in the production of fuller leathers with a shrinkage temperature of 113±2°C, exhibiting an exhaustion of 93% of chromium offered. The leathers were fuller, thereby minimising the use of dyes and retanning agents.
Example IX
60.0 gms of naphthalene was sulphonated with 135.0 gms of 98% sulphuric acid in a round bottom flask fitted with a stirrer at 120°C for 2 hrs. The sulphonated mass was transferred to a glass lined reaction vessel fitted with a stirrer and the mass was cooled down to 60°C.
12.8 gms of phthalic acid was added to the above mass with continuous stirring. 4.8 ml formaldehyde was added drop by drop keeping the temperature at 55-60°C using a thermostatic water bath for 15 min. 9.96 gms urea was dissolved in 4.8 ml of formaldehyde at a pH of 5.5. The urea-
formaldehyde adduct thus obtained was added to the reaction mixture and the reaction was allowed to continue for 60 min. 1.2 gms of oxalic and 6.8 gms of tartaric acid were added to the reactor along with 130 gms of ferrous sulphate. The temperature was maintained at 65°C and condensation was continued for 40 mins. The temperature was then raised to 75°C and condensation continued for 2 hrs. At this stage, 1 ml of the condensate was poured in 10 ml of water and was found to form a clear solution. The reaction mass was cooled to 30°C and was neutralised with 400 gms of sodium sulphite. The resulting mass was filtered and the filtrate was spray dried at 190°C with contact time of 5 sec. The resulting powder was packed in jute bag. A 1:10 solution of the product in water exhibited precipitation at a pH of 7.0.
This powder was used for the retanning of wet blue goat skins and resulted in the production of fuller leathers, exhibiting an exhaustion of 92% of iron offered. By striking with vegetable tanning materials a uniform black colour was obtained.
The advantages of the present invention are the following
1. The complex exhibits good solubility in water ensuring its use as a potential tanning agent.
2. The metal ion is in the complexed form and resists precipitation upto
a pH of 10.
3. Fuller leathers with minimised drawn grain effect are produced by
using the complex as a self tanning agent.
4. Exhibits around 90 - 95% exhaustion of metal ion.
5. Shelf life of the product is about 15-24 months.


We Claim:
1. A process for the preparation of novel organo-metallic polymeric matrix useful as tanning agent, which comprises
i) sulphonating an aromatic hydrocarbon, preferably naphthalene, anthraxcene, at 110 - 180°C for 1 - 3 hrs in conventional way, wherein the amount of sulphuric acid used for sulphonation is 3 - 5 moles per mole of the aromatic hydrocarbon, optionally adding organic ligand such as herein defined, to the mixture , at 40 - 60°C, wherein the amount of organic ligand used is 0.1 -10 moles per mole of the aromatic hydrocarbon,
ii) treating the reaction mixture, as formed in step (i) .with formaldehyde at 45 - 70°C over a period of 20 - 40 min,
iii) condensing the reaction mixture, as formed in step (ii), with a water soluble adduct comprising urea and formaldehyde at a ratio 1 : 1, at 45 - 70°C for a period of 20 - 60 min,
iv) complexing the condensate, as formed in step (iii) with organic ligand and a metal salt as described herein, at a temperature in the range of 50 - 95°C, for a period of 1 - 5 hrs,
v) neutralizing the reaction mixture by known method to pH 2 - 4 at 30 - 50°C,
vi) drying the filtrate of the reaction mixture, as formed in step (iii), by known method for 3-60 sec at a temperature in the range of 130-260°C to get novel organo-metallic polymeric matix.
2. A process as claimed in claim 1, wherein the organic ligand
used is selected from citric acid, phthalic acid, tartaric acid,
salicylic acid, oxalic acid, any alkali metal salt of these acids,
either individually or in combination.
3. A process as claimed in claims 1 & 2, wherein water soluble
adduct used is having a 1 : 1 molar ratio of urea and
formaldehyde.
4. A process as claimed in claims 1 to 3, wherein molecular weight
of the water-soluble adduct is in the range of 500 to 2000
Daltons.
5. A process as claimed in claims 1 to 4, wherein pH of the water-
soluble adduct is in the range of 3 to 6.
6. A process as claimed in claims 1 to 5, wherein the metal of
metal-salt used for anchoring to the organic polymeric matrix is
selected from zirconium, titanium, iron, aluminium, chromium.
7. A process as claimed in claims 1 to 6, wherein the salt of the
metal is in the form of sulphate, chloride, oxychloride either
individually or in combination.
8. A process as claimed in claims 1 to 7, wherein the amount of
metal salt used is 2 - 10 moles per mole of the aromatic
hydrocarbon.
9. A process for the preparation of novel organo-metallic polymeric matrix useful as tanning agent substantially as herein described with reference to the examples.


Documents:

3077-del-1998-abstract.pdf

3077-del-1998-claims.pdf

3077-del-1998-correspondence-others.pdf

3077-del-1998-correspondence-po.pdf

3077-del-1998-description (complete).pdf

3077-del-1998-form-1.pdf

3077-del-1998-form-19.pdf

3077-del-1998-form-2.pdf

3077-del-1998-form-3.pdf


Patent Number 215050
Indian Patent Application Number 3077/DEL/1998
PG Journal Number 10/2008
Publication Date 07-Mar-2008
Grant Date 20-Feb-2008
Date of Filing 20-Oct-1998
Name of Patentee COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH
Applicant Address RAFI MARG, NEW DELHI -100 001, INDIA
Inventors:
# Inventor's Name Inventor's Address
1 MOOKANDI KANTHIMATHI CENTRAL LEATHER RESEARCH INSTITUTE,ADYAR, CHENNAI - 600 020, INDIA
2 RAMASUBBU SUNDARAM CENTRAL LEATHER RESEARCH INSTITUTE,ADYAR, CHENNAI - 600 020, INDIA
3 KALARICAL JANARDHANAN SREERAM CENTRAL LEATHER RESEARCH INSTITUTE,ADYAR, CHENNAI - 600 020, INDIA
4 JONNALGADDA RAGHAVA RAO CENTRAL LEATHER RESEARCH INSTITUTE,ADYAR, CHENNAI - 600 020, INDIA
5 BALACHANDRAN UNNI NAIR CENTRAL LEATHER RESEARCH INSTITUTE,ADYAR, CHENNAI - 600 020, INDIA
6 THIRUMALACHARI RAMASAMI CENTRAL LEATHER RESEARCH INSTITUTE,ADYAR, CHENNAI - 600 020, INDIA
PCT International Classification Number C14C 3/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA