GB2105745A

GB2105745A - Fatting tanned leather

Info

Publication number: GB2105745A
Application number: GB08224616A
Authority: GB
Inventors: Werner Amati
Original assignee: Sandoz AG
Current assignee: Sandoz AG
Priority date: 1981-08-29
Filing date: 1982-08-27
Publication date: 1983-03-30
Also published as: DE3230925A1; IT8223012A0; NZ201746A; IT1153180B; DE3230925C2; CH655738A5; HK37088A; SG105887G; FR2512064B1; FR2512064A1; GB2105745B

Abstract

Tanned leather substrates are fatted by: a) applying to the substrate as the fatting agent an aqueous solution or dispersion of a phosphoric acid partial ester having attached to the phosphorus atom an average 1 to 2 (which may be a non-integral number) groups of the formula I <IMAGE> where each A independently is <IMAGE> and n is a number from 2 to 10 with the proviso that 2 to 6 groups A are <IMAGE> R is an unsubstituted linear or branched (preferably linear) C14-20alkyl group or an unsubstituted linear or branched (preferably linear) C14-20alkenyl group, the phosphoric acid partial ester being in free acid or salt form and b) treating with an agent selected from polyvalent metal oxide, hydroxide and salt, at the same time as fatting or after fatting.

Description

SPECIFICATION Improvements in or relating to organic compounds The invention provides a method of fatting tanned leather substrates comprising a) applying to the substrate as the fatting agent an aqueous solution or dispersion of an ortho phosphoric acid partial ester having attached to the phosphorus atom an average 1 to 2 (which may be a non-integral number) groups of the formula I

where each A independently is ACH2 or

and n is a number from 2 to 10 with the proviso that 2 to 6 groups A are -(CH2#2, R is an unsubstituted linear or branched (preferably linear) C,4~20aikyl group or an unsubstituted linear or branched (preferably linear) C,4~20alkenyl group, the phosphoric acid partial ester being in free acid or salt form; and b) treating with an agent selected from polyvalent metal oxide, hydroxide and salt, after fatting.

When the ortho phosphoric acid partial ester is in salt form the salts are preferably alkali metal (more preferably lithium, sodium or potassium; most preferably sodium or potassium) salts or ammonium salts (more preferably mono-, di- and trialkyl or alkanol ammonium salts).

Preferably R is R' where R' is an alkyl or alkenyl group derived from tetradecanoi, cetyi alcohol, oleyl alcohol, stearyl alcohol and tallow fat alcohol. More preferably R is R" where R" is C16-C18alkyl or alkenyl, most preferably C,6~,8alkyl.

Preferably n is n' where n' is 2 to 6, more preferably 3 to 5.

Most preferred groups of the formula I are of the formula I'

where R"' is cetyl or stearyl, and n' is 2 to 6.

Preferred ortho phosphoric acid partial esters are of the formula II

where M is hydrogen, an alkali metal or ammonium as defined above X is M (above defined) or AA0#nF1 where the symbols A and R, are defined below each R, independently is an unsubstituted C,4~20 linear or branched alkyl or a C1420 linear or branched alkenyl group, each A independently is4CH2 ) 2 or

n is a number from 2 to 10 with the proviso that 2 to 6 groups A are4CH242 and mixtures thereof.

In the above formulae the indices n are average values and the groups R have an average number of carbon atoms particularly in the case where R is derived from a mixture of alcohols.

In the above compounds of formula II in which X is M preferably one of the groups X or M is hydrogen and the other is an alkali metal or ammonium group.

In order to form the salt or partial salt of compounds of formula II, the compound of formula II is preferably treated in the presence of water with a base until a pH of 5 to 8 is reached preferably 6 to 8, more preferably 6 to 7.

Preferably the phosphoric acid partial esters used in the method of the invention are water-soluble or form a dispersion in water without the aid of additional dispersing agents. By "water soluble" is meant that the esters are soluble to the extent of at least 3 g/l, preferably 10 g/l at 200 in distilled water.

By the term "form a dispersion in water" is meant that on average the particle size in the dispersion is no greater than 5 (wm (preferably none of the particles is greater than 5 ltm) more preferably the particle size in the dispersion on average is no greater than 1 t(m (most preferably none of the particles is greater than 1 I > m.

In step b) where the agent is an polyvalent metal oxide, hydroxide or salt, an example of metal oxide is MgO and of metal hydroxide is Ca(OH)2. The metal salts are however preferred. Preferred cations of the agent are magnesium, calcium, barium, and more preferably aluminium, chromium (iii) and zirconyl.

Preferred agents are the water-soluble salts of the above metals, more preferably selected from aluminium sulphate, potassium chromium alum, chromium hydroxy sulphate, zirconylchloride, zirconyl sulphate, zirconyl acetate, chromium sulphate and aium.

Further, according to the invention there is provided an aqueous fatting composition comprising (i) an ortho-phosphoric acid partial ester having attached to each phosphorus atom an average 1 to 2 (which may be a non-integral number) groups of the formula I

where each A independently, isACH242 or CH3 QH2CH and n is a number from 2 to 10 with the proviso that 2 to 6 groups A areACH242; and R is an unsubstituted linear or branched C140alkyl group or an unsubstituted linear or branched C1420alkenyl group, the partial ester being in free acid or salt form; and (ii) a mono- or di-ethylene glycol mono (C2~8alkyl)ether and optionally a water soluble mono- or di-(C2~8)-aikylene glycol.

Preferred diethylene glycol monoalkyl ethers are those having Alkyl groups, more preferably C78alkyl groups. Preferred monoethylene glycol monoalkyl ethers are those having Alkyl groups more preferably C35alkyl groups. Of the glycol ethers of component (ii), the monoethylene glycol monoalkyl ethers are preferred.

The most preferred glycol ether of component ii is 2-n-butoxyethanol.

Preferred monoalkylene glycols of component ii are those having a C26alkylene group and preferred dialkylene glycols are those having C23-alkylene groups. The monoalkylene glycols are more preferred to the dialkylene glycols.

Preferably the fatting compositions of the invention may include one or more further additive selected from (ii) a non-fatting hydrocarbon oil, (iv) isopropanol; and (v ) up to 1% by dry weight of component (i) of an anti-foaming agent and/or a fungicide. Preferably when components (iii) and or (iv) are present, component (ii) includes a monoalkylene glycol in the fatting composition of the invention.

Preferred non-fatting hydrocarbon oils are in general natural, semi-synthetic and synthetic hydrocarbons that are liquid at room temperature (200C) and have a boiling point, of 250 C and below.

Preferred oils are substantially pure aliphatic or substantially aliphatic oils in particular petroleum ether (boiling point 80-11 00C) and white spirit (b.p. 150--2500C). White spirit having a boiling point in the range 200-2500C, is most preferred.

Preferred fatting compositions of the invention in aqueous solution or dispersion (with no component (iii) or (iv) above) comprise: 30 - 80% by weight of component (i) 4 - 30% by weight of component (ii) 10 - 66% by weight of water.

More preferably fatting compositions of the invention in aqueous solution or dispersion (with no components (iii) or (iv) above) comprise: 60 - 75% by weight of component (i) 5 - 25% by weight of component (ii) 15 - 35% by weight of water.

Preferred aqueous fatting compositions of the invention (including components (iii) and (iv) above) comprise: 20 - 55% by weight of component (i) 3 - 20% by weight of component (ii) 7 - 45% by weight of water 3,5 - 45% by weight of component (iii) 10 - 30% by weight of component (iv) with the proviso that components (ii) and (iii) comprise at least 14% by weight of the composition.

More preferred aqueous fatting compositions of the invention (including components (iii) and (iv) above) comprise: 40 - 52% by weight of component (i) 4 - 15% by weight of component (ii) 10 - 24% by weight of water 8 - 26% by weight of component (iii) 6 - 20% by weight of component (iv) with the proviso that components (ii) and (iii) comprise at least 20% by weight of the composition.

The compositions comprising components (iii) and (iv) are preferred to those not containing components (iii) and (iv).

The concentration of after-treatment agent used with respect to the dry weight of phosphoric acid partial ester used is preferably 1 to 100%, more preferably 5 to 20%.

The phosphoric acid partial esters are known and may be produced according to known methods for example the reaction of mono- or poly-alkylene glycol mono ether with phosphorus pentoxide, phosphoroxy chloride or polyphosphoric acid, more preferably with phosphorus pentoxide.

The compounds of component (ii) are known and may be produced (for example by the reaction of alcohol with alkylene oxide in the presence of a catalytic amount of an alkali metal hydroxide to form the mono- or poly-alkylene glycol ethers. Components (iii), (iv) and (v) are known and may be made according to known methods.

Fatting compositions according to the invention may be formed according to known methods for example by mixing the individual components (i) and (ii) and optionally water, component (iii) component (iv) and component (v) together.

One preferred method for preparing an aqueous fatting composition of the invention containing no components (iii) and (iv) is first to oxyalkylate the C1420alkanol or alkenol to the required degree then treat with phosphoric acid an hydroxide or phosphoroxy chloride or an hydroxide or a polyphosphoric acid to produce the phosphoric partial ester. After this, the partial ester may be treated with an appropriate base to give the required salt at a pH of 5-8 and then the partial ester is mixed with component (ii).

The addition of base alternatively may be after the addition of component (ii) and then water may be added thereafter.

A further method for preparing fatting compositions including components (iii) and (iv) comprises melting component (i) and then component (ii) is added to the melt at a temperature from 20-1 000C.

Then base may be added and then isopropanol followed by component (iii) and then followed by the addition of water. The pH of the composition is preferably 5 to 8. If further additivess such as antifoaming agents and fungicides are to be present these can be added as the last component to the composition.

The fatting compositions (preferably in aqueous form) according to the invention are preferably applied to leather according to known fatting methods using aqueous solutions.

For fatting leather the fatting compositions of the invention preferably containing components (iii) and (iv) may be directly added as the fatting agent. The oil-containing compositions are stable to storage. One test for stability to storage is to heat the composition to 500C and then allow it to cool to 200C and then leave the composition for 24 hours at 200C (room temperature). The composition is stable to storage if it is not significantly changed at the end of this period.

Preferred leather substrates are those which have been tanned, for example naturally tanned leather, combined tanned or synthetically tanned leather (for example chrome tanned, zirconyl tanned, aluminium tanned leather) or leather that is re-tanned.

Preferred leather substrates are grain leather for example nappa from sheep or goat or box leather from calf or cow or cow hide or velours leathers preferably from sheep, goat or cow, and more preferably hunting leather, split velour from cow or calf skin and nubuk leather. Also fur velours may be so treated.

Optionally the leather may be dyed before treatment with the phosphoric acid partial ester.

Preferred dyestuffs are those usual for dyeing leather, more preferably anionic, metal-free or metalised azo dyestuffs.

Fatting of leather may be carried out according to known methods for example exhaustion or impregnation (for example by padding, spraying or foam-treating). Exhaustion is however preferred.

Preferably the concentration of phosphoric acid partial ester (with reference to the folding weight of leather treated) is 0.2 to 1 5%, more preferably 2 to 8%.

The aqueous fatting bath preferably has a pH of from 2 to 9, more preferably from 4 to 7.The pH adjustment may be carried out by the addition of appropriate acid, base or buffer solution, preferably formic acid or ammonium or alkali-metal-carbonate.

The preferred temperatures for fatting leather are from 20 to 70"C, more preferably from 40 to 600C.

The treated leather may be dried and finished according to known methods.

The treatment with metal oxide, hydroxide or salt may be applied by exhaustion or impregnation (for example padding, spraying or foam-treating). Exhaustion from aqueous medium is more preferred.

The agent may be added to the fattening bath on termination of the fatting process using the same aqueous medium as is used for the fatting process.

The treatment with metal oxide, hydroxide or salt is preferably carried out at 20 to 700C, more preferably 40 to 600 C.

The pH of the treatment is preferably 2 to 9, more preferably 4 to 7. The pH adjustment may be carried out by the addition of appropriate acid, base or buffer solution preferably formic acid or ammonium- or alkali-metal carbonate.

After treatment with the above agent, the leather may be finished according to known methods.

Leather when treated according to a fatting method according to the invention or with a fatting composition according to the invention, optionally followed by a treatment with metal oxide, hydroxide and/or salt, shows good tear resistance and hydrophobicity and is supple for instance has a good handle and has good fastness properties related to leather, in particular fastness to dry cleaning.

The invention will now be illustrated by the Examples in which all parts and percentages are by weight and all temperatures are in OC, unless indicated to the contrary.

EXAMPLE 1 270.5 g of stearyl alcohol and 0.5 g of pulverised sodium hydroxide are placed in a 1.5 1 fournecked flask and heated to 1 500 C. The flask is evacuated and then filled with ethylene oxide. 176 g of ethylene oxide are introduced at normal pressure and at a temperature of 1 50-1 900 C. At the end of the reaction the flask is flushed with nitrogen and cooled to 700.71 g of phosphorus pentoxide are added, portion by portion at 7080 . After the addition the reaction mixture is left to react for 6-8 hours at 75 to 800. Then the reaction produced is poured into 1 645 g of 2.43% sodium hydroxide and a 25% neutral solution of the phosphoric partial ester forms.

EXAMPLE 2 In an analogous fashion to the method of Example 1,242.5 g of cetyl alcohol is reacted with 1 74 g of 1,2-propyleneoxide followed by 264 g of ethylene oxide and then the mixture is reacted with 85 g of polyphosphoric acid (having a P205 content of 8384%). Then the reaction product is poured into 1 570 g of a 3.6% solution of potassium hydroxide to give a neutral 35% viscous paste.

EXAMPLE 3 In an analogous manner to Example 1 268 g of oleyl alcohol is ethoxylated with 132 g of ethylene oxide and then reacted with 71 g of phosphorus pentoxide. Then the reaction product is poured into 1140 g of 1.5% ammonia solution to give 1 628 g of a viscous product having 30% active substance.

EXAMPLE 4 a. In an analogous manner to Example 1, 260.4 g of tallow fat alcohol (having a hydroxyl number of 21 5) is ethoxylated with 1 67 g of ethylene oxide and finally reacted with 71 g of phosphorus pentoxide at 50-600C to form 498 g of the phosphoric half ester. b. Alternatively, 260.4 g of of tallow fat alcohol may be ethoxylated with 1 98 g of ethylene oxide followed by reacting with 1 53.5 g of phosphoroxy chloride may be used at 400C followed by a 5 hour reaction at 600C instead of the phosphorus pentoxide). Then the phosphoric partial ester is poured in 1 500 ml of water and then neutralised with sodium hydroxide to a pH of 7.

EXAMPLE 5 Instead of pouring the phosphoric partial ester into sodium hydroxide solution, in the method of Example 1,133 g of 2-isopropoxyethanol is added dropwise to the reaction product (at the end of the 6-8 hour period) at 500.68 g of a 25% ammonia solution is added and the mixture is diluted with 617 g of water to produce a paste containing 40% active substances.

EXAMPLE 6 Instead of pouring the reaction product of Example 2 into potassium hydroxide, 270 9 of 2-ethoxy ethanol is poured in at a temperature of 5060 and the product is converted to the appropriate salt by the addition of 61 g of monoethanolamine and then diluted with 310 g of water to give a 60% active substances product.

EXAMPLE 7 Instead of pouring the phosphoric partial ester into ammonia solution in Example 3, the reaction mixture is diluted with 810 g of 2-(n-hexyloxy) ethanol, reacted with 149 g of triethanolamine and finally diluted with 206 g of water. The resultant mixture contains 30% active substances.

EXAMPLE 8 Instead of pouring the phosphoric partial ester into waterfollowed by neutralization with NaOH in Example 4,80 g of 2-(n-butoxy)ethanol is added, reacted with 134.6 g of triethanolamine to give the appropriate salt and then diluted with 176 g of water. The resulting paste contains 72% active substances.

EXAMPLE 9 Instead of pouring the phosphoric partial ester into water followed by neutralization with NaOH in Example 4a, 80 g of 2-(n-butoxy)ethanol is added, reacted with 1 34.6 g of triethanolamine to give the appropriate salt, then diluted with 214 g of isopropanol,145 g of water and finally 214 g of white spirit (b.p. 201--2430).

EXAMPLES lotto 16 In a similar manner to the method of Example 9, the following amounts of reactants may be used, given as a percentage by weight of the total amount of reactants.

Amount of Ex. phosphorus 2 Amount of Amount of Amount of Amount of No. ester 2-alkoxy alcohol isopropanol White Spirit water 10 50% 4.3% of 2-(n- 11.7% 11% 22.3% butoxy)ethanol 11 50% 12.5% of 2-(n- 14% 14% 9.5% butoxy)ethanol 12 50% 1 9.3% of 2-(n- 24.7% 16% butoxy)ethanol 13 50% 6.3% of hexylene 16.7% 16.7% 10.3%.

glycol 14 50% 6.3% of 2-ethoxy 16.7% 16.7% 10.3% ethanol 15 50% 6.3% of 2-isopro- 16.7% 16.7% 10.3% poxy ethanol 16 30% 4% of 2-butoxy- 10% 10% 46% ethanol The phosphorus half ester referred to in the table above is that of Example 9.

The products are pourable ranging from viscous to easily flowable.

In the following Application Examples A to C all percentages used are with reference to the folding weight of substrate treated unless indicated to or clearly to the contrary. The chromium hydroxy sulphate has a Cr203 content of 25%.

APPLICATION EXAMPLE A (Box leather from cow) A piece of wet-blue leather is immersed in 200% water for 5 minutes at 400. The piece is then treated for 30 minutes with 2% chromium hydroxy sulphate and 4% dimethylolethyleneurea; after which it is treated with 6% mimosa extract and 1% of the dyestuff C.l. (Colour Index) Acid Brown 359 for 1 hour and then 250% water at 40 and 0.3% of an 85% aqueous formic acid solution are added.

The piece is then fatted for 45 minutes in a bath of 200% water and 20% of the preparation Example 1 having 5% active substance with respect to the piece treated). After this the piece is immersed for 30 minutes in 2% chromium hydroxy sulphate and 0.3% of an 35% aqueous formic acid solution. The leather is washed with 200% water at 200, after which the leather is hung to dry overnight.

Instead of using the preparation of Example 1 , any of the preparations of Examples 2 to 1 6 may be used.

APPLICATION EXAMPLE B (Hunting leather) A wet-blue cowhide iss immersed in 1 50% water at 30 and is tanned with 5% chromium hydroxy sulphate for 3 hours. The hide is then washed for 10 minutes with 200% water at 400, after which the hide is immersed in a bath of pH 6.5 to 7 containing 200% water at 350 and ammonium bicarbonate.

The hide is then washed with 200% water at 350 and then in a bath of 3% of the dyestuff C.l. Acid Brown 126 and 1% of a 25% ammonia solution for 45 minutes. After this, the hide is fatted by applying 23% of the preparation of Example 2 (having 8% active substances with respect to the hide) at 450 for 1 hour. The hide is then fixed by treating with 2% chromium hydroxy sulphate and 2% of an 85% aqueous formic acid solution for 30 minutes. The hide is then hung to dry overnight.

Instead of the preparation of Example 2, the preparations of Example 1, and 3 to 1 6 may be used in appropriate amounts.

APPLICATION EXAMPLE C (Velours from sheep) A piece of wet-blue sheep's celt is immersed in 800% water at 56 and 2% of a 25% aqueous solution of ammonia for 1 hour. The pelt is then tanned with 3% zirconylsulphate after which the pelt is treated with 600% water at 50 and 1% of a 25% aqueous solution of ammonia for 10 minutes. The pelt is then dyed in a bath containing 4% of the dyestuff C.i. Acid Brown 303 for 60 minutes, after which it is fatted by treating with 10% of a preparation of Example 9 (having 5% active substances with respect to the pelt) for 60 minutes. After fatting the pelt is fixed by treating with 2% chromium hydroxy sulphate and 2% of an 85% aqueous formic acid solution for 40 minutes after which the pelt is hung to dry overnight.

Instead of the preparation of Example 9, any of the preparations of Examples 1 to 8 and 10 to 1 6 may be used in appropriate amounts.

Claims

1. A method for fatting tanned leather substrates comprising a) applying to the substrate as the fatting agent an aqueous solution or dispersion of an ortho phosphoric acid partial ester having attached to the phosphorus atom an average 1 to 2 (which may be a non-integral number) groups cf the formula I

where each A independently is ACH2X- or CH3 -CH2-CH- and n is a number from 2 to 10 with the proviso that 2 to 6 groups A are (CH2#, R is an unsubstituted linear or branched (preferably linear) C1420alkyl group or an unsubstituted linear or branched (preferably linear) C,4~20alkenyl group, the phosphoric acid partial ester being in free acid or salt form; and b) treating with an agent selected from polyvalent metal oxide, hydroxide and salt, after fatting.

2. A method as claimed in Claim 1, in which R is R' where R is an alkyl or alkenyl group derived from tetradecanol, cetyl alcohol, oleyl alcohol, stearyl alcohol and tallow fat alcohol.

3. A method as claimed in Claim 2, in which R is R", where R" is C1518alkyl or alkenyl.

4. A method as claimed in any one of the preceding claims, in which n is n' where n' is 2 to 6.

5. A method as claimed in any one of the preceding claims, in which the groups of formula I are of the formula I'

where R" is cetyl or stearyl, and n' is 2 to 6;

6. A method as claimed in Claim 1, in which the orthophosphoric acid partial esters are of the formula Il

where M is hydrogen, an alkali metal or ammonium; X is M (above defined) or #A-O#R1 where the symbols A and R1 are defined below each R, independently is an unsubstituted C14-20 linear or branched alkyl or a C14-20 linear or branched alkenyl group, each A independently is#CH2##2 or

7. A method as claimed in any one of the preceding claims, in which the agent is selected from aluminium sulphate, potassium chromium alum, chromium hydroxy sulphate zirconyl chloride, zirconyl sulphate and zirconyl acetate.

8. A fatting composition comprising (i) an ortho- or pyro-phosphoric acid partial ester having attached to each phosphorus atom an average 1 to 2 (which may be a non integral number) groups of the formula I

where each A independently, is4CH242 or

and n is a number from 2 to 10 with the proviso that 2 to 6 groups A are ACH2k; and R is an unsubstituted linear or branched C1420alkyl group or an unsubstituted linear or branched C1420alkenyl group, the partial ester being in free acid or salt form; and (ii) a mono- or di-ethylene glycol mono (C28aIkyl)ether and optionally a water soluble mono- or di-(C28)-alkylene glycol.

9. A fatting composition as claimed in Claim 8, in which the ortho orpyrophosphoric acid partial ester is of formula Il or Ill

where M is hydrogen, an alkali metal or ammonium, X is M (above defined) or #A-O#nR1 where the symbols A and F1 are defined below each R, independently is an unsubstituted C,4~20 linear or branched alkyl or a C 14-20 linear or branched alkenyl group each A independently is CH2#2 or

n is a number from 2 to 10 with the proviso that 2 to 6 groups A are -(CH2#2, and mixtures thereof.

10. A fatting composition as claimed in Claim 9, in which R is R", where R" is C16~18alkyl or alkenyl.

11. A fatting composition as claimed in Claim 9 or Claim 10, in which n is n' were n' is 2 to 6.

12. A fatting composition as claimed in any one of Claims 9 to 11, in which component (ii) is selected from monoethylene glycol (C26alkyl)ether and diethylene glycol (Cs~8alkyl)ethers and optionally mono (C26)alkylene glycol and di(C2~3)alkylene glycol.

1 3. A fatting composition as claimed in any one of Claims 8 to 12, including one or more additives selected from (iii) a non-fatting hydrocarbon oil; (iv) isopropanol and (v) up to 1% by dry weight of component (i) of an anti-foaming agent and/or fungicide.

14. A fatting composition as claimed in any one of Claims 8 to 1 2 comprising 30 - 86% by weight of component (i) 4 - 30% by weight of component (ii) 10 - 66% by weight of water.

15. A fatting composition as claimed in Claim 1 4 comprising 60 - 80% by weight of component (i) 5 - 25% by weight of component (ii) 15 - 35% by weight of water.

16. A fatting composition as claimed in Claim 13 comprising 20 - 55% by weight of component (i) 3 - 20% by weight of component (ii) 7 - 45% by weight of water 3,5 - 45% by weight of component (iii) 0 - 30% by weight of component (iv) With the proviso that components (ii) and (iii) comprise at least 14% by weight of the composition.

1 7. A fatting composition as claimed in Claim 1 6 comprising 40 - 52% by weight of component (i) 4 - 15% by weight of component (ii) 10 - 24% by weight of water 8 - 26% by weight of component (iii) 6 - 20% by weight of component (iv) with the proviso that components (ii) and (iii) comprise at least 20% by weight of the composition.

18. A method as claimed in Claim 1 substantially as herein described with reference to any one of Examples A to C.

19. A composition as claimed in Claim 8 substantially as herein described with reference to any one of Examples 5 to 16.

20. A tanned leather substrate when fatted according to a method as claimed in any one of Claims 1 to 7 and 18.

21. A tanned leather substrate when treated with a fatting composition as claimed in any one of Claims 8 to 17 and 19.

22. A tanned leather substrate as claimed in Claim 20 or Claim 21 selected from nappa from sheep or goat or box leather from calf or cow hide or velours leathers, hunting leather, split velours from cow or calf skin, nubuk leather and fur velours.

23. A tanned leather substrate as claimed in any one of Claims 20 to 22, in which the leather has been dyed prior to fatting.