AU2004204169A1 - Method for degreasing animal skins at ultralow interfacial surface tension - Google Patents

Description

IN THE MATTER of a PCT Application in the name of BASF Aktiengesellschaft filed under PCT/EP 04/000069 and IN THE MATTER OF its transfer for an Application for an Australian Patent I, Gtinter Isenbruck, Dr. phil.nat., Dipl.Chem., Patentanwalt and European Patent Attorney in Mannheim (F.R.G.), do solemnly and sincerely declare that I am conversant with the English and German languages and am competent in translating thereof, and that the following is, to the best of my knowledge and belief, a true and correct translation of the International Patent Application filed under No. PCT/EP 04/000069 by BASF Aktiengesellschaft for ,, Degreasing animal hides by means of ultralow surface tension" Mannheim, June 16, 2005 inter Isenbruck - Patentanwalt - "as originally filed" 5 Degreasing animal hides by means of ultralow surface tension The present invention relates to compositions which are used for removing fats from substrates selected from the group consisting of hides, skins, pelts and further intermediate 10 products in leather production and fur production, a process for removing fats from said substrates, the use of said compositions during the removal of fats from the substrates, and degreasing agents containing alcohol alkoxylates and substrates selected from the group consisting of hides, skins, pelts and further intermediate products in leather production and fur production, containing these alcohol alkoxylates. 15 The removal of natural fat from animal hides is important for the production of high quality leathers and fur skins, particularly in the case of animal hides having medium and high natural fat contents. The distribution of finishing chemicals in the leather and fur production stages following the degreasing is substantially improved by the degreasing so 20 that, for example, uniform tanning and dyeing are possible. If the natural fat is not removed, in the case of leather the end product is spotted and/or, as a result of bacterial degradation of the fats and crystallization of the high molecular weight saturated fatty acids during storage, acquires fatty spews which may adversely affect the leathers visually and physically. In the case of fur skins, a nonuniformly dyed suede side is observed, and in 25 addition local hardening with risk of breaking of the fur skin occurs. According to the prior art, substantially two processes for degreasing animal hides are used: solvent degreasing and emulsifier degreasing. 30 The solvent degreasing is degreasing using organic solvents. It an be effected either without addition of water (dry degreasing) or in the presence of water (wet degreasing). Owing to the use of organic solvents, solvent degreasing leads to considerable environmental pollution, which is already no longer acceptable in many countries.

-2 For these predominantly ecological reasons, emulsifier degreasing, which completely dispenses with the use of organic solvents, is predominantly carried out today. Suitable emulsifiers in this process are in particular nonionic surfactants, since these have no capability of binding to the hide or leather fibers. Thus, they can optimally solubilize the 5 natural fat of the animal hides without being hindered by interactions with the animal hide. Known nonionic emulsifiers are addition compounds of ethylene oxide and/or propylene oxide with alkylphenols, alcohols or fatty acids. The nonionic surfactants most frequently used over decades are the alkylphenol ethoxylates. However, there are ecological and toxicological reservations about the surfactant class consisting of the alkylphenol 10 ethoxylates, so that the use of alkylphenol ethoxylates is voluntarily dispensed with in Germany and some other countries. Alcohol ethoxylates are predominantly used as a substitute for the alkylphenol ethoxylates. EP-A 0 281 486 relates to biologically stabilized, untanned hides and a process for the 15 production of these hides. According to EP-A 0 281 486, degreasing of pickled hides is effected by adding a certain amount of emulsifier whose determined hydrophilic-lipophilic balance (HLB) is identical to the required hydrophilic-lipophilic balance (RHLB) of the natural fats contained in the hides, together with a cosurfactant in the presence of salts at a temperature above the melting point of the fats. According to examples 2, 4 and 6, a 20 mixture of emulsifier and cosurfactant in an amount of about 4% by weight is used for degreasing, the emulsifier accounting for 60 (examples 2 and 4) or 95 (example 6) parts of the mixture. Por6 (Ind. Ciur 5 (1986), 22 to 25) relates to a discussion on the degreasing of pickled and 25 pretanned hides. The degreasing is carried out with drumming of a mixture of emulsifiers and cosurfactants, the exact mixture depending on the type of fats to be removed. Instead of a liquor being used, the mixture is applied directly to pickled hides which have been allowed to drip off or to hides stored in pickle. Thorough impregnation is effected, the hydrophobic fraction of the emulsifiers coming into contact with the fats in order to 30 promote emulsification during washing. After the degreasing, the pickled hides are washed with sodium chloride solution in a short liquor. According to the procedure disclosed, the -3 degreasing is effected without a liquor, using from 2 to 4% of a suitable emulsifier. The suitable emulsifier depends on the fat type of the hides to be degreased. DE-A 100 05 669 relates to a process for degreasing skins, in which pickled skins are 5 degreased by treatment with a nonionic surfactant which comprises an adduct of from 4 to 16 mol of ethylene oxide with a C 10 - to C 16 -fatty alcohol. The surfactant is used in a concentration of from 10 to 50 g/l of liquor. WO 00/12660 relates to a process for increasing the efficiency of surfactants, surfactant 10 mixtures which additionally contain block copolymers having a water-soluble block A and a water-insoluble block B as an additive being used (efficiency booster). No information is given in WO 00/12660 about the amount of surfactant or of surfactant and additive used. Although the result achieved according to the prior art with respect to the removal of fats 15 from animal hides and other substrates is satisfactory, it is desirable to provide compositions and processes by means of which the degreasing result can be further improved, in particular without increasing the amount of surfactant used or to achieve a degreasing result which is the same as or better than that achieved by the process of the prior art using smaller amounts of surfactant. 20 It is an object of the present invention to provide compositions which can be used for removing fats from animal hides and other substrates and a process for degreasing animal hides and other substrates, excellent degreasing results being achieved and in particular small amounts of surfactant being used. Such compositions and processes are desirable 25 from the economic and ecological point of view. We have found that this object is achieved by a composition comprising a) a fat phase which contains fats from hides, skins, pelts or further intermediate 30 products in leather production and fur production; b) at least one surfactant; and c) an aqueous phase; and -4 d) if required, further assistants and additives, wherein the surface tension between the fat phase and the aqueous phase is from 1 to 10- 9 mNm-1 at from 15 to 45'C. 5 Excellent degreasing results are obtained using this novel composition, in general even small amounts of surfactant being sufficient for achieving these excellent results. The surface tension between the fat phase and the aqueous phase is preferably from 0.5 to 10 10-1, particularly preferably from 10-1 to 10-9, mm-1. This-surface tension is achieved at from 15 to 45'C, preferably from 20 to 45*C, particularly preferably from 25 to 40*C. The temperatures are the optimum temperatures for carrying out a process for removing fats from the abovementioned hides, skins, pelts and further intermediate products in leather production and fur production. 15 It has been found that excellent degreasing results are obtained at the novel surface tension between fat phase and aqueous phase. Fat phase 20 The fat content of the hide of different animal breeds varies in some cases considerably and also varies within the animal breeds. Thus, cattle hides have a fat content of from 0 to 2% by weight, goat skins a fat content of from 0.5 to 3.5% by weight and sheep skins a fat content of from 1.5 to 10% by weight, based on the pelt weight. The pelts contain, as a 25 rule, from 60 to 80% by weight of water. Surfactants The hides, skins, pelts and further intermediate products in leather production and fur 30 production which are mentioned as substrates contain fats having different compositions. It is therefore difficult to provide exact information about which surfactants are most suitable -5 in the novel compositions. However, the optimum surfactants can be determined by simple routine experiments. In principle, it is possible to use anionic, cationic, amphoteric or nonionic surfactants or 5 mixtures thereof. Suitable anionic surfactants are C 10 - to C 2 0-alkylsulfates, preferably C 12 - to C1 6 alkylsulfates, e.g. sodium dodecylsulfate; C 10 - to C 2 0-alkylpolyethersulfates, preferably C12- to C 1 6 -alkylpolyethersulfates, e.g. sodium dodecyloxypolyethoxysulfates; alkali metal 10 salts of diisooctylsulfosuccinic acid; alkali metal salts of alkylbenzenesulfonic acids, e.g. sodium dodecylbenzenesulfonate, of dialkylphosphates and of carboxylates, e.g. of fatty alkyl ether carboxylates. Suitable cationic surfactants are, for example, alkyltrimethylammonium halides having 15 alkyl chain lengths of about 8 to 12 carbon atoms and/or quaternized imidazolinium or pyridinium salts. Suitable nonionic surfactants which are preferably used in the novel composition are addition compounds of ethylene oxide and/or propylene oxide with alkylphenols, alcohols 20 or fatty acids. The nonionic surfactants most frequently used over decades are the alkylphenol ethoxylates. In particular, nonylphenol ethoxylate having on average 9 EO (ethylene oxide) units was used. Also suitable and more environmentally compatible than the alkylphenol ethoxylates are alcohol ethoxylates, in particular alcohol alkoxylates having alkyl chain lengths of C 7 to C 18 , preferably C 7 to C 16 , and from 2 to 50, preferably 25 from 3 to 20, oxyalkylene, in particular oxyethylene, oxypropylene and/or oxybutylene units, or block copolymers of these units. Nonionic surfactants having an HLB value of >8, preferably >10, very particularly >12, are particularly preferably used (the HLB value was calculated (Pord, Ind. Ciur 4 (1987) 21 30 to 23)).

-6 Alcohol alkoxylates which have a polydispersity D of in general > 1.22, preferably >1.25, are very particularly preferably used. It is possible to use an individual surfactant which has said polydispersity or a surfactant mixture, the mixture having said polydispersity (D = polydispersity = M, / Mn, where M, and Mn are determined by means of gel permeation 5 chromatography (GPC): GPC conditions: - Mobile phase: THF 1.0 ml/min. - Internal standard: toluene 10 - Detector: DURATEC RI 2000 - Column (3 units): 8 x 300 mm PSS SDV 105A 5 pm, 1000 A 5p, 100 A 5pm + precolumn SDV 5[ (8 x 50mm) - 20 I injected volume Measurement temperature: room temperature.) 15 Nonionic surfactants particularly preferably used in the novel composition are alcohol alkoxylates which are obtained by reacting at least one alcohol ROH with n mol of at least one alkylene oxide per mole of alcohol ROH, where 20 - R is an alkyl radical of 5 to 30 carbon atoms which has a main chain which is the longest alkyl chain of the radical R, having 4 to 29 carbon atoms, which is branched in the middle of the chain, beginning with carbon atom C2, the numbering starting from the carbon atom (C1) which is bonded directly to the oxygen atom adjacent to the radical R, and ending with the carbon atom o-2, where o is the terminal carbon 25 atom of the main chain, C2 and the carbon atom o-2 being included, with at least one C1- to Cro-alkyl radical; - the alkylene oxide has 2 to 6 carbon atoms and 30 - n is from 1 to 100.

-7 Such Guerbet alcohol alkoxylates and their use as degreasing agents are disclosed in the non-prior-published application with the application number PCT/EP02/07245 and with the title "Lederentfettungsmittel" [Leather degreasing agents]. Guerbet alcohol alkoxylates based on 2-propylheptanol are very particularly preferred, in particular those which contain 5 both ethylene oxide units and propylene oxide units, very particularly preferred Guerbet alcohol alkoxylates being those which are alkoxylated first with propylene oxide and then with ethylene oxide in a block procedure. n in said alcohol alkoxylates is particularly preferably from 1 to 50, very particularly 10 preferably from 1 to 30. Particularly preferably used surfactants are therefore one or more alcohol alkoxylates which are obtained by reacting at least one alcohol ROH with n mol of at least one alkylene oxide per mole of alcohol ROH, where 15 - R is an alkyl radical of 5 to 30 carbon atoms which has a main chain which is the longest alkyl chain of the radical R, having 4 to 29 carbon atoms, which is branched in the middle of the chain, beginning with the carbon atom C2, the numbering starting from the carbon atom (C1), which is bonded directly to the oxygen atom 20 adjacent to the radical R, and ending with the carbon atom o)-2, where 0) is the terminal carbon atom of the main chain, C2 and the carbon atom 03-2 being included, with at least one Ci- to Cio-alkyl radical; - the alkylene oxide has 2 to 6 carbon atoms and 25 - n is from 1 to 100, preferably from 1 to 50, particularly preferably from 1 to 30, the individual alcohol alkoxylates or a mixture of alcohol alkoxylates having a polydispersity D of >1.22, preferably >1.25. 30 A particular advantage of the novel composition is that excellent degreasing results are obtained even with the use of small amounts of surfactant. Thus, the surfactants are used in -8 the novel compositions in an amount of in general from >0 to 500, preferably from >0 to 100, particularly preferably from >0 to 50, very particularly preferably from >0 to 25, parts by weight, based on the mass of the fat phase. 5 The amounts of the components in the novel compositions are stated in parts by weight in the present application. In practice, the tanner uses in some cases percentages by weight for corresponding data. Aqueous phase 10 In addition to the fat phase and the at least one surfactant, the novel composition contains an aqueous phase comprising water. This may additionally contain at least one salt selected from alkali metal and alkaline earth metal salts. Particularly preferred salts are sodium chloride, potassium chloride, sodium formate and sodium acetate. Sodium chloride is very 15 particularly preferably used. The salt or the salts is or are present in the aqueous phase - if they are contained in the aqueous phase - in an amount of in general from >0 to 1 000, preferably from >0 to 500, particularly preferably from >0 to 200, parts by weight, based on the fat phase. 20 Moreover, the aqueous phase may contain further compounds which influence the hydrophilic-lipophilic balance, in particular of the aqueous phase. Such compounds are, for example, hydrophilic organic compounds, such as short-chain alcohols or acids, e.g. alcohols of 1 to 6, preferably 1 to 3, carbon atoms, such as ethanol, or acids having 1 to 6, 25 preferably 1 to 3, carbon atoms in the alkyl radical of the acid, such as acetic acid, or polyalcohols, such as glycerol, polyglycerol, polyvinyl alcohols and sorbitol. Further compounds which influence the hydrophilic or the hydrophobic character of the aqueous phase are, for example, hydrophobic organic compounds, such as relatively long-chain fatty alcohols or fatty acids, preferably fatty alcohols or fatty acids having 7 to 50, 30 particularly preferably 10 to 30, carbon atoms in the alkyl or alkenyl radical of the fatty alcohols or fatty acids.

-9 These further compounds which influence the hydrophilic-lipophilic balance, in particular of the aqueous phase, are used - if they are contained in the aqueous phase - in an amount of in general from >0 to 1 000, preferably from >0 to 500, particularly preferably from >0 to 200, parts by weight, based on the fat phase. 5 These further compounds have a substantial effect on the surface tension in the novel compositions. This must be taken into account when choosing the surfactant. Suitable combinations of surfactants and further compounds which influence the hydrophilic or hydrophobic character of the aqueous phase for the novel compositions can be determined 10 in a few routine experiments familiar to a person skilled in the art. Assistants and additives The novel compositions may also contain further assistants and additives. 15 Suitable further assistants and additives are preferably selected from the group consisting of efficiency boosters and lipases. Suitable efficiency boosters are known to a person skilled in the art. Efficiency boosters 20 based on a block copolymer having at least one water-soluble block A and at least one water-insoluble block B are preferably used. The block copolymers preferably have a structure according to the pattern AB, ABA or BAB. Particularly preferably, a polyethylene oxide is used as block A and a polydiene or an at least partly hydrogenated polydiene as block B. Such efficiency boosters are disclosed, for example, in 25 WO 00/12660. The efficiency boosters are used - if they are contained in the novel composition - in an amount of in general from >0 to 250, preferably from >0 to 30, particularly preferably from >0 to 10, parts by weight, based on the fat phase. 30 Furthermore, the novel compositions may contain lipases. Nature synthesizes and degrades fats, for example, with the aid of lipases in a variety of ways. The decomposition of the fats -10 results in the formation of glycerol, fatty acids, monoglycerides and diglycerides, which influence the surface tension between the fat phase and the aqueous phase since they are surface-active. Owing to their hydrophilic head group and the hydrophobic tail, the fatty acids formed during the decomposition have an amphiphilic character, as do the 5 monoglycerides and diglycerides formed. If it is now assumed that amphiphiles form during the decomposition of the fats, this results in a substantial effect with respect to the surface tension in the novel compositions since effectively one or more surface-active compounds form from a fat owing to the decomposition. 10 In a further embodiment of the present invention, the novel compositions therefore contain lipases which are capable of degrading the fats contained in the composition to give surface-active compounds which have an advantageous effect on the surface tension. Owing to the (partial) conversion of the fat into surface-active components, the amount of surfactant to be used can be considerably reduced. 15 The lipases are used - if they are contained in the novel composition - in an amount of in general from >0 to 250, preferably from >0 to 30, particularly preferably from >0 to 10, parts by weight, based on the fat phase, in the novel compositions. 20 When lipases are used, it must be borne in mind that the surface tension in a composition containing a given surfactant changes. In order to obtain optimum degreasing results, it is therefore necessary to match any lipases used and the surfactants used according to the invention with one another. The suitable combinations can readily be determined by a person skilled in the art by means of routine experiments. In general, the use of lipases 25 requires the use of, for example, alkoxylated alcohol alkoxylates having a relatively high degree of ethoxylation n of, preferably, n > 8, particularly preferably n > 15. The novel compositions generally have a pH of from 1 to 14, preferably from 2 to 12, particularly preferably from 5 to 9. 30 In a particularly preferred embodiment, the novel compositions contain the following components: - 11 a) a fat phase which contains fats from hides, skins, pelts or further intermediate products in leather production and fur production; b) from >0 to 500, preferably from >0 to 100, particularly preferably from >0 to 50, 5 parts by weight, based on the fat phase, of at least one surfactant, preferably of a nonionic surfactant, particularly preferably of an alcohol alkoxylate; c) from >0 to 5 000, preferably from >0 to 1 000, particularly preferably from >0 to 500, parts by weight, based on the fat phase, of an aqueous phase, containing water 10 and if required, either c1) from >0 to 1 000, preferably from >0 to 500, particularly preferably from >0 to 200, parts by weight, based on the fat phase, of at least one salt, preferably sodium chloride 15 and/or c2) from >0 to 1 000, preferably from >0 to 500, particularly preferably from >0 to 200, parts by weight, based on the fat phase, of further compounds which influence the hydrophilic-lipophilic balance, in particular of the aqueous phase, preferably hydrophilic organic compounds, such as short-chain 20 alcohols or acids, e.g. alcohols of 1 to 6, preferably 1 to 3, carbon atoms, such as ethanol, or acids having 1 to 6, preferably 1 to 3, carbon atoms in the alkyl radical of the acid, such as acetic acid, or polyalcohols, such as glycerol, polyglycerol, polyvinyl alcohols and sorbitol; or hydrophobic organic compounds, such as relatively long-chain fatty alcohols or fatty 25 acids, e.g. fatty alcohols or fatty acids having 7 to 50, particularly preferably 10 to 30, carbon atoms in the alkyl or alkenyl radical of the fatty alcohols or fatty acids; d) from >0 to 250, preferably from >0 to 30, particularly preferably from >0 to 10, 30 parts by weight, based on the fat phase, of further assistants and additives, preferably efficiency boosters and/or lipases.

-12 These novel compositions are very suitable for degreasing hides, skins, pelts and/or further intermediate products in leather production and fur production or wool. Said substrates are preferably used in depickled form. 5 The present invention furthermore relates to a process for removing fats from substrates selected from the group consisting of hides, skins, pelts and further intermediate products in leather production and fur production, comprising the following steps: a) bringing the substrates to be degreased into contact with a degreasing agent 10 comprising at least one surfactant and an aqueous phase which contains water, if required at least one salt and, if required, further compounds which influence the hydrophilic-lipophilic balance, in particular of the aqueous phase, at from 15 to 45'C; 15 b) forming a composition comprising a fat phase which contains fats from hides, skins, pelts or further intermediate products in leather production and fur production, the at least one surfactant and the aqueous phase, which contains water and, if required, at least one salt and, if required, further compounds which influence the hydrophilic-lipophilic balance, in particular of the aqueous phase, 20 and, if required, further assistants and additives, the surface tension in the fat phase and the aqueous phase being from 1 to 10-9 mm-1 ((partial) dissolution of the fat); c) increasing the surface tension between the fat phase and the aqueous phase of the composition to a surface tension of >1 mNm~1, a fat phase, an aqueous phase and an 25 aqueous surfactant phase being formed (removal of the fat). The novel process gives excellent degreasing results and furthermore permits simple and complete removal of the fat obtained from the hides, skins, pelts and further intermediate products in leather production and fur production (substrates). 30 Steps a) to c) can, if required, be followed by further steps. For example, it is conceivable for step c) to be followed by a washing step (step d)) in which washing is effected - 13 preferably with a surfactant-containing mixture. The exact composition of the surfactant containing mixture used in the washing step and the procedure in the washing step are known to a person skilled in the art. Preferably used surfactants are the abovementioned surfactants. The washing step can be carried out once or, if required, repeated one or more 5 times. Alternatively, it is also possible to repeat steps a) to c) and, if required, d) in the novel degreasing process once or several times. This is preferable in particular in the case of substrates having high fat contents. The repeated implementation of steps a) to c) and, if 10 required, d) is effected under conditions known to a person skilled in the art. The individual steps of leather production or fur production, such as soaking, liming, fleshing and splitting, bating, pickling, tanning, samming, sorting by quality criteria, shaving, neutralizing, filling, dyeing, fatliquoring, drying, staking and finishing and the 15 reaction conditions and starting materials preferred in these steps are known to a person skilled in the art. The degreasing of said substrates which is effected by the novel process can be carried out in different process stages in leather production and fur production. 20 Preferably, degreasing of the pickled substrates is effected since particularly good and complete degreasing is then achieved. Step a) 25 The subsequent bringing of the substrates to be degreased into contact with a degreasing agent (step a)) can be carried out in all suitable apparatuses known to a person skilled in the art, for example in a tanning drum. 30 Step a) is effected at from 15 to 45*C, preferably from 20 to 45'C, particularly preferably from 25 to 45'C. In general, an increase in the temperature leads to an increase in the degree of degreasing.

- 14 The duration of step a) of the novel process is in general from 0.5 to 10, preferably from 0.5 to 5, hours, particularly preferably from 0.5 to 3, hours. 5 The surfactants used in the novel process, the amount of surfactants used, the amount and type of any salt used, the amount and type of any further compounds used which influence the hydrophilic-lipophilic balance, in particular of the aqueous phase, and the assistants and additives used and the amount thereof correspond to the information provided with regard to the novel composition. 10 The novel degreasing process (step a)) can be carried out in the liquor or without a liquor, i.e. only with the internal liquor of the pelts. If the process is carried out without a liquor, in general addition of the degreasing agent to the substrates to be degreased and subsequent milling are effected. 15 Step b) The surface tension of the composition formed in step b), between the fat phase and the aqueous phase, is preferably from 0.5 to 10-9, particularly preferably from 10-1 to 10-9, 20 mNm-1. This surface tension is achieved at from 15 to 45'C, preferably from 20 to 45*C, particularly preferably from 25 to 40'C. The temperatures are the optimum temperatures for carrying out a process for removing fats from the abovementioned hides, skins, pelts or further intermediate products in leather production and fur production. 25 Step c) The surface tension between the fat phase and the aqueous phase of the composition can be increased in various ways. Thus, it is possible on the one hand to change the temperature of the composition formed in step b) or to reduce the salt concentration in the composition 30 formed in step b) or to change the amount of any further compounds used which influence the hydrophilic-lipophilic balance, in particular of the aqueous phase, or, in step c), to add - 15 those compounds which influence the hydrophilic-lipophilic balance, in particular of the aqueous phase, and thus to change the polarity of the aqueous phase. In a preferred embodiment, the surface tension of the composition formed in step b) is 5 increased by reducing the concentration of the salt present in the aqueous phase if the aqueous phase in step a) contains at least one salt. The reduction of the concentration of the salt present in the aqueous phase is most simply achieved by dilution with water. The salt concentration is generally reduced to from <5 to 10 <3, preferably <2, parts by weight. In a further preferred embodiment, the surface tension of the composition formed in step b) is increased by changing the temperature of the composition formed in step b). 15 It is also possible to increase the surface tension of the composition formed in step b) by a combination of a plurality of said procedures. For example, a temperature change can be effected simultaneously with a reduction of the salt concentration of the composition. The fat phase obtained thereby can be separated off by methods known to a person skilled 20 in the art. The separation is effected, for example, in a phase separator or by centrifuging. In general, three phases form: a fat phase, an aqueous phase and an aqueous surfactant phase: - the fat phase contains solubilized fat and may contain small amounts of hydrophobic 25 surfactant components dissolved therein, - the aqueous phase may contain at least one salt and, if required, further compounds which influence the hydrophilic-lipophilic balance, in particular of the aqueous phase, and, if required, small amounts of hydrophilic surfactant components dissolved in the 30 aqueous phase, and -16 - the aqueous surfactant phase contains the main part of the surfactant components and small amounts of fat. The aqueous surfactant phase can be used again in step a) of the novel process. Thus, the 5 novel process can be carried out in an economical and ecological manner since the amount of surfactant to be used can be further reduced by this recycling. By means of the novel process or the novel compositions, efficiencies (difference between the fat content before degreasing and after degreasing) x 100/(fat content before 10 degreasing) of 50%, preferably of 60%, particularly preferably of > 70%, can be achieved in leather degreasing. The present invention furthermore relates to the use of the novel composition for removing fats from substrates selected from the group consisting of hides, skins, pelts and further 15 intermediate products in leather production and fur production. Excellent degreasing results can be achieved by the novel use. The present application furthermore relates to degreasing agents for the treatment of hides, 20 skins, pelts and further intermediate products in leather production and fur production, based on nonionic surfactants of the alcohol alkoxylate type, one or more alkyl alkoxylates being used, which are obtained by reacting at least one alcohol ROH with n mol of at least one alkylene oxide per mole of alcohol ROH, where 25 - R is an alkyl radical of 5 to 30 carbon atoms which has a main chain which is the longest alkyl chain of the radical R, having 4 to 29 carbon atoms, which is branched in the middle of the chain, beginning with the carbon atom C#2, the numbering starting from the carbon atom (C#1) which is bonded directly to the oxygen atom adjacent to the radical R, and ending with the carbon atom o-2, where o is the terminal carbon 30 atom of the main chain, C#2 and the carbon atom co-2 being included, with at least one

C

1 - to Cio-alkyl radical; - 17 - the alkylene oxide has 2 to 6 carbon atoms and - n is an integer from 1 to 100, preferably from 1 to 50, particularly preferably from 1 to 30, 5 the individual alcohol alkoxylates or a mixture of alcohol alkoxylates having a polydispersity D of >1.22, preferably >1.25. With the aid of the novel alcohol alkoxylates or alcohol alkoxylate mixtures, emulsions 10 which have high emulsion stability, i.e. fat-carrying capacity and permit excellent removal of the fat (step c)) are obtained, so that subsequent deposition of the fat dissolved out of the pelts in step b) is avoided. Such Guerbet alcohol alkoxylates and their use as degreasing agents are disclosed in the 15 non-prior-published application having the application number PCT/EP02/07245 and the title "Lederentfettungsmittel" [Leather degreasing agents]. Compared with the non-prior published application having the application number PCT/EPO2/07245 and the title "Lederentfettungsmittel" [Leather degreasing agents], it was found that alcohol alkoxylates having a high polydispersity of an individual alcohol alkoxylate or of a mixture of alcohol 20 alkoxylates of D >1.22, preferably >1.25, are particularly effective. Guerbet alcohol alkoxylates based on 2-propylheptanol are very particularly preferred, in particular those which contain both ethylene oxide units and propylene oxide units, those Guerbet alcohol alkoxylates which are alkoxylated, first with propylene oxide and then with ethylene oxide in the block procedure being very particularly preferred. 25 Preferred embodiments of the degreasing agents and of components in the degreasing agents are disclosed in PCT/EP02/07245. The novel degreasing agents very particularly preferably additionally contain one or more 30 lipases and/or one or more efficiency boosters. Suitable lipases and efficiency boosters are mentioned above.

- 18 The present invention furthermore relates to degreased substrates selected from the group consisting of hides, skins, pelts and further intermediate products in leather production and fur production, comprising the alcohol alkoxylates contained in the abovementioned degreasing agents. 5 The alcohol alkoxylates are present in the degreased substrates in an amount of in general from >0 to 3, preferably from >0 to 2, parts by weight, particularly preferably from >0 to 1 part by weight, based on the degreased pelts. 10 The examples which follow additionally illustrate the invention. Examples 15 Degreasing experiments were carried out on pickled and washed sheepskins. For this purpose, in each case about 2 kg of pelts were degreased at 30'C. The important parameters of the degreasing experiments are as follows: 20 - constant temperature, T = 30 'C - first short liquor of 30 parts by weight of water in the first degreasing step, including about 8 parts by weight of salt with surfactant according to the data in table 2 (1st dose) - lengthening of the first liquor with 120 parts by weight of water, so that the salt concentration is reduced to about 2 parts by weight 25 - second long liquor with 100 parts by weight of water and surfactant according to the data in table 1 (second dose) In the attached table 2, the degreasing formulation used in the processes according to the examples is shown.

-19 The following surfactants were used: - Lutensol AP 9 (nonylphenol ethoxylate having on average 9 ethylene oxide (EO) units, D = 1.08) 5 - Eusapon LD 6031 (branched C10-alcohol alkoxylate having first on average 1.5 propylene oxide (PO) units and then 6 EO units, D = 1.23) - Lutensol XL 60 (branched C10-alcohol alkoxylate having first on average 1.2 propylene oxide (PO) units and then 6 EO units, D = 1.06) - Lutensol A04 (C13C15-oxo alcohol ethoxylate having on average 4 EO units, D = 10 1.07) - Lutensol A07 (C13C15-oxo alcohol ethoxylate having on average 7 EO units, D = 1.10) - Lutensol AO 11 (C13C15-oxo alcohol ethoxylate having on average 11 EO units, D = 1.12) 15 - PIBA 1000 + 11 EO (polyisobutylene amine having 11 EO units) D = polydispersity = M, / M,, where M, and Mn are determined by means of gel permeation chromatography (GPC): GPC conditions: 20 - Mobile phase: THF 1.0 ml/min. - Internal standard: toluene - Detector: DURATEC RI 2000 - Column (3 units): 8 x 300mm PSS SDV 105A 5 srm, 1000 A 5um, 100 A 5[m + 25 precolumn SDV 5[m (8 x 50mm) - 20 RI injected volume - Measurement temperature: room temperature Table 1 below shows the results of the degreasing experiments.

- 20 Table 1: Results of the degreasing experiments Expe- Degreasing agent Dose Fat content of the Surface tension of the Leather riment liquor first short liquor assessment 1st 2nd 1st [%] 2nd [%] [mNm '] M1% [%] 150% 100% water water V1 Lutensol" AP9 1 2 2 2 1.19 2 V2 Lutensol" A07 1 2 3 2 1.26 2 V3 Lutensol" AO11 1 2 2 2 1.8 2 V4 Eusapon" LD 6031 1 2 1 2 1.2 4 Lipase LBR1 0.1 0 El Lutensol" XL60 1 2 1 2 0.83 2 E2 Eusapon LD 6031 1 2 2 3 0.37 1 E3 Eusapon" LD 6031 0.8 1.6 2 3 0.25 1 E4 Cio-OH with 1,5 1 2 2 3 0.09 1 PO and 20 EO + Lipase LBR1 0.1 0 E5 Lutensol" A07 + 0.7 2 2 3 0.08 2 (PIBA 1000 + 0.1 0 1lEO) E6 2nd liquor (split) - 2 3 1 0.009 1 comprising E2 in 1st liquor + Eusapon LD 6031 in 2nd liquor 1) Surfactant dose in % by weight, based on the amount of water used; 1st = dose in the first short 5 liquor, 2nd = dose in the second long liquor; 2) fat content of the liquor in % by weight, based on the amount of water used 3) the degreased pelts were assessed visually: 1 = excellently degreased (back of the neck and flanks grease-free) 2 = very well degreased (back of the neck grease-free, flanks slightly greasy) 10 3 = well degreased (back of the neck and flanks slightly greasy) 4 = satisfactorily degreased (back of the neck and flanks greasy) 5 = poorly degreased ("fat spots") 6 = very poorly degreased ("fat spots" and in parts no degreasing) 1 .1. VJlJUU.ILL\J U . -21 Evaluation of the results of the degreasing experiments: - V1 to V3 give well degreased leathers having a relatively high surface tension in theIst liquor. In comparison, El with the lowest surface tension leads to a better result. The combination of (ultra)low surface tension and the use of surfactants or surfactant 5 mixtures having a broad molecular weight distribution further improves the result (E2) or permits a further reduction in the amount of surfactant used (E3). As a result of the broader molecular weight distribution, better emulsion stability of the dilute first liquor and the second liquor for removing fat is achieved, i.e. the fat-carrying stability is increased with the result that improved removal of the fat is achieved. 10 - For using a lipase (V4), the very good result of E2 becomes poorer, which can be explained by the formation of hydrophobic surfactant fractions from the fats and hence a shift in the hydrophilic-lipophilic balance of the phases, which leads to an increase in the surface tension, resulting in a poorer degreasing result. If however, as described in E4, a more highly ethoxylated alkoxylate is used, a very low surface tension is once 15 again obtained leading to a very good degreasing result. - The use of efficiency boosters (E3) leads to the same result as V3, with the reduced amount of surfactant. - Heating the 2nd liquor from E2 to 65'C leads to splitting of the emulsion into 3 phases. The use of the aqueous surfactant-rich phase as the 1st liquor in E6 leads to the same 20 very good result as E2 or E3. Thus, a third of the amount of surfactant can be saved. Measurement of the surface tension by means of the spinning-drop tensiometry: The principle of spinning-drop tensiometry was developed in 1942 by Vonnegut [1] and is 25 one of the classical methods of measurement in which the surface tension is derived from the geometric shape of a drop present in the external field. For this purpose, the two phases to be investigated are introduced into a capillary rotating about the horizontal axis. Under the influence of the centrifugal force and of the surface tension, the lighter phase assumes, in equilibrium, the shape of a drop extended along the axis of rotation, the diameter of 30 which drop is measured as a function of the rotational velocity. In the investigations carried out here, the surface tensions were measured using a Kriiss SITE 04 spinning-drop tensiometer. This type of tensiometer was developed by Cayias et - 22 al. [2] and modified by Burkowsky and Marx [3]. It makes it possible to measure surface tensions in a range of 10 1 <6/mNm1/<10 4 . It consists of a thermostatable glass capillary which can rotate at a maximum of 10 000 rpm about its longitudinal axis. At the respective measurement temperature, after the phase equilibrium has been established, the fat phase 5 was injected into the rotating capillary which had been filled with the aqueous phase, in order to determine the surface tension 6 ab between these two phases. The surface tensions were calculated according to Vonnegut [1]. He considered the drop as a cylinder having a radius r, a length 1 and hemispherical ends. For drops where 1 >> r, the surface tension can be calculated using 10 6 = 1/4 (pi - P2)2 r. Here, o) is the angular velocity and (pi - P2) is the density difference of the two phases [4, 5]. 15 The statistical error in the spinning-drop measurements carried out is only about 1-2%. The systematic error, which is due to temperature variations or possible impurities in the sample on withdrawal, is, however, in the range of up to 10% and thus accounts for the main component. The temperature inaccuracy is about ± 0.1 'C. 20 References [1] B. Vonnegut, Rev. Sci. Instr. 13 (1942), 6. [2] J.L. Cayias, R.S. Schechter and W.H. Wade, in: Adsorption at Interfaces, ed. by K.L. Mittal, ACS Symposium Series Vol. 8, Washington, DC, 1975. 25 [3] M. Burkowsky and C. Marx, Tenside Detergents 155 (1978), 247. [4] T. Sottmann and R. Strey, Ber. Bunsenges. Phys. Chem. 100, 3 (1996), 237. [5] T. Sottman, Dissertation, G6ttingen (1998).

- 23 Table 2: Degreasingfonnulation Parts by Component Temperature Ratio with Time pH weight [C] water [min] 1st degreasing 30 Water 30 8 Salt 1.5 Sodium carbonate x Surfactant 10 Plus skins 60 120 Water (dilution) 30 10 4.5-5 Liquor discharged Washing 200 Water 30 10 Liquor 10 discharged 2nd degreasing 100 Water 30 x Surfactant 60 Liquor 10 discharged Washing (2x) 200 Water 30 10 Liquor discharged Tanning 40 Water 20 (pickled) 7 Salt 10 + 1.0 Formic acid 1:10 15 2.5 + 0.5 Sulfuric acid 1:10 120 -24 + 6 Chromitan* 120 FM + 0.45 Neutrigan* not 4,0 MO/MON specified on horse, sam, shave, finish After the abovementioned steps, retanning, dyeing and fatliquoring and subsequent drying are carried out by methods known to a person skilled in the art. The drying is followed by assessment.

Claims (6)

1. A composition comprising a) a fat phase which contains fats from hides, skins, pelts or further intermediate 5 products in leather production and fur production, b) at least one surfactant and c) an aqueous phase and d) if required, further assistants and additives, 10 wherein the surface tension between the fat phase and the aqueous phase is from 1 to

10- 9 mNm' at from 15 to 45'C. 2. A composition as claimed in claim 1, wherein the surface tension is from 0.5 to 10-9 mNm-, preferably from 10~1 to 10~9 mm-'. 15 3. A composition as claimed in claim 1, wherein the surfactants used are nonionic surfactants, preferably alcohol alkoxylates. 4. A composition as claimed in any of claims 1 to 3, wherein the surfactants are used in 20 a concentration of from >0 to 500, preferably from >0 to 100, particularly preferably from >0 to 50, parts by weight, based on the amount of the fat phase. 5. A composition as claimed in any of claims 1 to 4, wherein aqueous phase contains, if required, at least one salt selected from alkali metal and alkaline earth metal salts 25 and/or further compounds which influence the hydrophilic-lipophilic balance, in particular of the aqueous phase. 6. A composition as claimed in any of claims 1 to 5, wherein the assistants and additives are selected from the group consisting of efficiency boosters and lipases. 30 7. A process for removing fats from substrates selected from the group consisting of hides, skins, pelts and further intermediate products in leather production and fur production, comprising the following steps: a) bringing the substrates to be degreased in contact with a degreasing agent 35 comprising at least one surfactant and an aqueous phase which contains water, if - 26 required at least one salt and, if required, further compounds which influence the hydrophilic-lipophilic balance, in particular of the aqueous phase, at from 15 to 45'C; b) forming a composition comprising a fat phase which contains fats from hides, 5 skins, pelts or further intermediate products in leather production and fur production, the at least one surfactant and the aqueous phase which contains water and, if required, at least one salt and, if required, further compounds which influence the hydrophilic-lipophilic balance, in particular of the aqueous phase, and, if required, further assistants and additives, the surface tension between the 10 fat phase and the aqueous phase being from I to 10' mNm'; c) increasing the surface tension between the fat phase and the aqueous phase of the composition, preferably to a surface tension of >1 mNm 1 , a fat phase, an aqueous phase and an aqueous surfactant phase being formed. 15 8. A process as claimed in claim 7, wherein the increase in the surface tension between the fat phase and the aqueous phase of the composition is achieved in step c) by changing the temperature of the composition formed in step b), reducing the concentration of any salt present in the aqueous phase, changing the amount of any further compounds used which influence the hydrophilic-lipophilic balance, in 20 particular the aqueous phase, and/or adding compounds which influence the hydrophilic-lipophilic balance, in particular of the aqueous phase. 9. A process as claimed in claim 7 or 8, wherein the surfactants used are nonionic surfactants, preferably alcohol alkoxylates. 25 10. A process as claimed in claim 7 or 8, wherein the alcohol alkoxylates have a polydispersity of >1.22.

11. A process as claimed in any of claims 6 to 10, wherein the surfactants are used in a 30 concentration of from >0 to 500, preferably from >0 to 100, particularly preferably from >0 to 50, parts by weight, based on the amount of the fat phase.

12. A process as claimed in any of claims 6 to 11, wherein the assistants and additives are selected from the group consisting of the efficiency boosters and lipases. 35 - 27 13. The use of a composition as claimed in any of claims 1 to 6 in the removal of fats from substrates selected from the group consisting of hides, skins, pelts and further intermediate products in leather production and fur production. 5 14. A degreasing agent for the treatment of hides, skins, pelts and further intermediate products in leather production and fur production, based on nonionic surfactants of the alcohol alkoxylate type, one or more alkyl alkoxylates being used, which are obtained by reacting at least one alcohol ROH with n mol of at least one alkylene oxide per mole of alcohol ROH, where 10 - R is an alkyl radical of 5 to 30 carbon atoms which has a main chain which is the longest alkyl chain of the radical R, having 4 to 29 carbon atoms, which is branched in the middle of the chain, beginning with the carbon atom C#2, the numbering starting from the carbon atom (C#1) which is bonded directly to the oxygen atom adjacent to the radical R, and ending with the carbon atom o-2, 15 where o is the terminal carbon atom of the main chain, C#2 and the carbon atom co-2 being included, with at least one C 1 - to CIO-alkyl radical; - the alkylene oxide has 2 to 6 carbon atoms and - n is an integer from 1 to 100, 20 the individual alcohol alkoxylates or a mixture of alcohol alkoxylates having a polydispersity D of >1.22.

15. A degreased substrate selected from the group consisting of hides, skins, pelts and further intermediate products in leather production and fur production, comprising 25 Guerbet alcohol alkoxylates.

16. A degreased substrate as claimed in claim 15, wherein Guerbet alcohol alkoxylates having a polydispersity of >1.22 are used.