Deliming composition and deliming method for deliming hides and skins

Abstract

The present invention relates to a deliming composition and a deliming method using a graft polymer product of a polysaccharide and / or polypeptide or a corresponding derivative thereof, obtainable by free radical polymerization of at least one monomer selected from acrylic acid or methacrylic acid or a mixture thereof or a monomer mixture thereof.

Description

[0001] The present invention relates to a deliming composition, a deliming method for deliming hides and skins, and the use of graft polymers as deliming agents for deliming hides and skins. The present invention particularly relates to deliming hides and skins with the aid of specific graft polymer products.

[0002] In the leather industry, liming of hides for dehairing and swelling (e.g., to remove unwanted proteins) is carried out in an alkaline medium, usually with the aid of inorganic or organic sulfides, at a pH of 12 or higher. Lime is typically used as the alkaline medium, usually alone but sometimes mixed with caustic soda or soda. To prepare the material for further processing, the liming chemicals, especially lime, are then removed again—a process known as "deliming." This step is often accomplished by adding an acid or acid salt that forms a highly soluble complex with calcium ions, thereby allowing the calcium ions to be removed with the wastewater. Furthermore, the pH of the hides should be brought to a desired, essentially neutral value, as the enzymes used in subsequent treatment steps to achieve swelling are optimized within this pH range. Examples of such acids include, in particular, phthalic acid, thiophthalic acid, formic acid, acetic acid, boric acid, aliphatic dicarboxylic acids and mixtures thereof, hydrochloric acid, sulfuric acid and its ammonium salts, and carbon dioxide.

[0003] Although deliming agents should be used until the pH in the cross-section of the hide is lowered, the pH should not drop below the isoelectric point of the proteins, i.e., below a pH of approximately 5, during this process. If this occurs, proteinaceous substances that entered the solution during the previous liming (in some cases together with other dissolved particles) precipitate and become difficult to remove on the surface of the hide. These residues render the hide surface unacceptable and interfere with subsequent processing, particularly dyeing. Furthermore, the feel of the resulting end product (leather) is adversely affected.

[0004] For this reason, most acids can only be added gradually in very small doses so that even in short-term and localized cases the pH does not fall below about 5, which is not achievable or only conditionally achievable due to fluctuations in the amount of lime present in the system during the tanning process.

[0005] For this reason, ammonium salts, which have a buffer range around pH 9 and are therefore less likely to lower the pH to critical levels, have been most commonly used for deliming until now. Furthermore, ammonium salts are readily available and economically attractive worldwide due to their use as fertilizers. However, this use has its drawbacks. On the one hand, ammonia gas is released during the deliming process, which, in addition to odor pollution, can also cause respiratory irritation to operators of the corresponding facilities. On the other hand, the wastewater contains large amounts of ammonia nitrogen, which is problematic from an environmental perspective. For this reason, the amount of ammonia nitrogen in wastewater discharged from tanneries is strictly regulated by law.

[0006] Therefore, in order to avoid the above problems, a variety of alternative deliming agents have been developed.

[0007] The use of butyrolactone as a deliming agent is known from DE 804 827. This lactone hydrolyzes under typical deliming conditions and thus provides a mild pH profile during the process. However, the hydrolysis proceeds very slowly and thus the treatment time is only realistic under certain conditions.

[0008] EP 0 059 909 A1 uses five- or six-membered ring carbonates of aliphatic polyols, such as ethyl carbonate or 1,2-propyl carbonate, as deliming agents. When using these deliming agents, the pH value does not exceed 7.5. Here, too, this effect is based on alkaline hydrolysis of the esters. As with butyrolactone, these compounds suffer from a slow hydrolysis process, which in some cases requires an unrealistically long time.

[0009] WO 2013 / 107233 A1 discloses another deliming agent. This deliming agent consists of polysuccinimide or hydroxypolysuccinimide. Its buffering effect is based on the ring opening of polysuccinimide in alkali and provides a stable pH control during deliming. However, due to the polymeric nature of these compounds, they not only penetrate the hide relatively slowly but also do not spread widely.

[0010] EP 3 425 068 A1 proposes amino acids and / or protein hydrolysates containing amino acids as deliming agents. The advantage here is that the amphoteric properties of the amino acids provide pH buffering during the process. Furthermore, amino acids form soluble calcium salts. However, this is only applicable to a limited extent for most protein hydrolysates, in which the active nitrogen groups and carboxyl groups are blocked by peptide bonds. Although the degree of hydrolysis is not specified in detail, it is subsequently mentioned in the patent that a high degree of hydrolysis associated with a high amino acid content is preferred, as amino acids are described as actual deliming agents. However, due to the high degree of hydrolysis, the hydrolysis of any protein source becomes relatively costly.

[0011] In EP 3 425 069 A1, protein hydrolysates are proposed as deliming agents, which can be obtained by acidic hydrolysis of hair, leather scraps or other residual substances produced during leathermaking. Amino acids are also described as active deliming agents here. The necessity of a relatively expensive hydrolysis with a high degree of hydrolysis can be seen by the hydrolysis under high pressure shown in the examples, which makes it necessary to use an autoclave for the hydrolysis.

[0012] The object of the present invention is therefore to provide a method for deliming hides and skins which at least partially overcomes at least one of the disadvantages of the prior art. In particular, the object of the present invention is to provide a simple method for deliming hides and skins which reduces or avoids the use of ammonium salts and in which the deliming agent used is based entirely or partly on the use of recycled natural polymers.

[0013] This object is achieved by the deliming composition according to the invention. According to the invention, this object is also achieved by the method according to the invention for deliming raw hides, the method according to the invention for preparing leather, and the use according to the invention. Preferred embodiments of the invention are disclosed in the dependent claims, the description, and the examples, wherein the other features described or illustrated in the dependent claims, the description, or the examples may form the subject matter of the invention individually or in any combination (if they do not clearly conflict from the context).

[0014] The present invention relates to a deliming composition for deliming hides and skins, wherein the deliming composition comprises at least:

[0015] - hides and skins to be delimed; and

[0016] a deliming agent, wherein the deliming agent comprises a graft polymerization product of at least one of a polysaccharide, a polypeptide or a derivative thereof, wherein the derivative of the polysaccharide is an oxidatively, hydrolytically or enzymatically degraded polysaccharide, an oxidized hydrolytically degraded polysaccharide or an oxidized enzymatically degraded polysaccharide or a chemically modified degradation product of such a polysaccharide, an oligosaccharide or a chemically modified monosaccharide, an oligosaccharide or a polysaccharide, and wherein the derivative of the polypeptide is a hydrolytically or enzymatically degraded and optionally chemically modified polypeptide,

[0017] The graft polymer product can be obtained by free radical polymerization of:

[0018] A) A monomer selected from the following monomers or a mixture of the following monomers

[0019] (a) acrylic acid or methacrylic acid or a mixture thereof or an alkali metal salt, alkaline earth metal salt or ammonium salt thereof, and optionally at least one of (b) and (c), wherein

[0020] (b) comprises other monoethylenically unsaturated monomers different from monomer (a) that are copolymerizable with monomer (a), and wherein

[0021] (c) a monomer having at least two ethylenically unsaturated non-conjugated double bonds in the molecule,

[0022] If at least one of the following exists:

[0023] B1) polysaccharides, oxidatively, hydrolytically or enzymatically degraded polysaccharides, oxidatively hydrolytically degraded polysaccharides or oxidatively enzymatically degraded polysaccharides or chemically modified degradation products of these, chemically modified monosaccharides, oligosaccharides or polysaccharides or mixtures of the compounds given, and

[0024] B2) Polypeptides, hydrolytically or enzymatically degraded and optionally chemically modified polypeptides or mixtures of the given compounds.

[0025] Surprisingly, it has been found that, in particular due to the presence of specific graft polymer products, the deliming compositions described here can achieve the above-mentioned objects as deliming agents with regard to the deliming of hides and skins to be delimed.

[0026] The deliming composition first comprises the hides to be delimed. It should be noted that deliming is, in a manner known per se, a process step following, for example, liming or dehairing within the leather industry. Such hides to be delimed are also referred to as bare hides. Bare hides are distinguished by the fact that the hair and / or fat content has been reduced, or, specifically, after liming, the hair and / or fat adhering to the hair has been removed by liming. Thus, for example, limed hides consist solely of pure hides, in particular without hair and, in particular, without fat residues.

[0027] The limed hides and skins, for example, still contain the substances used for liming. Examples of these include calcium hydroxide and sodium sulfide, slaked lime, sodium sulfide, and various enzymes. Furthermore, the hides and skins to be delimed have a pH value in the alkaline range due to the upstream treatments, in particular in the pH range of greater than 9, for example greater than or equal to 10, and in most cases greater than or equal to 11.

[0028] However, these substances must be removed from the hides or pelts in order to prepare them for tanning, another process step known per se in leathermaking. This step is particularly deliming, which also serves to prepare the hides for tanning. During deliming, substances used, for example, for liming are removed from the hides, and the pH is also lowered, optimally to a substantially neutral range. This can be achieved using deliming agents. Thus, after deliming, the hides have a pH value ranging from approximately 7 to 9.

[0029] Deliming agents are therefore used in particular to lower the pH from the alkaline range to the essentially neutral range, and by deliming, for example, liming substances can be removed.

[0030] According to the present invention, the deliming agent essentially comprises a graft polymerization product of a polysaccharide, a polypeptide and / or a derivative thereof, wherein the polysaccharide derivative is an oxidatively, hydrolytically or enzymatically degraded polysaccharide, an oxidized hydrolytically degraded polysaccharide or an oxidized enzymatically degraded polysaccharide or such chemically modified degradation products or chemically modified monosaccharides, oligosaccharides or polysaccharides, and wherein the polypeptide derivative is a hydrolytically or enzymatically degraded and optionally chemically modified polypeptide.

[0031] The graft polymer product can be obtained by free radical polymerization of:

[0032] A) A monomer selected from the following monomers or a mixture of the following monomers

[0033] (a) acrylic acid or methacrylic acid or a mixture thereof or an alkali metal salt, alkaline earth metal salt or ammonium salt thereof, and optionally at least one of (b) and (c), wherein

[0034] (b) comprises other monoethylenically unsaturated monomers different from monomer (a) that are copolymerizable with monomer (a), and wherein

[0035] (c) comprising monomers having at least two ethylenically unsaturated non-conjugated double bonds in the molecule,

[0036] If at least one of the following exists:

[0037] B1) polysaccharides, oxidatively, hydrolytically or enzymatically degraded polysaccharides, oxidatively hydrolytically degraded polysaccharides or oxidatively enzymatically degraded polysaccharides or chemically modified degradation products of these, chemically modified monosaccharides, oligosaccharides or polysaccharides or mixtures of the compounds given, and

[0038] B2) Polypeptides, hydrolytically or enzymatically degraded and optionally chemically modified polypeptides or mixtures of the given compounds.

[0039] Thus, surprisingly, it has been found that the objects of the present invention can be achieved using graft polymers of polysaccharides and / or polypeptides or their corresponding derivatives, which can be obtained by free radical polymerization of monomers selected from a monomer mixture of at least acrylic acid or methacrylic acid or a mixture thereof. Such graft polymers based on natural polymers are known, and their preparation is described, inter alia, in WO 2012 / 163823 or DE 4416877. In contrast to these documents, in which the corresponding polymers are used for tanning, i.e., in a treatment step subsequent to deliming, the advantages of the above-mentioned polymers as deliming agents have been surprisingly discovered.

[0040] These compounds make it possible to achieve the stated objects without requiring complex hydrolysis of natural polymer components (for example in the case of leather shavings) up to a high degree of hydrolysis, even though they are of polymeric nature.

[0041] Advantageously, the polymer component can comprise a natural polymer component. Natural polymer components are understood here to include all types of polysaccharide and polypeptide sources. Examples thereof include, in particular, starch, leather shavings, leather flakes, bone glue, hair, and feathers, which can serve as polysaccharides and polypeptides.

[0042] In order to form a deliming composition, a deliming auxiliary agent, a buffer salt, an organic acid or a proteolytic enzyme may also be added to the graft polymerization for deliming.

[0043] The deliming aid may be a magnesium salt, sugar, and / or molasses. The buffer salt may be selected from sodium pyrosulfate, sodium bisulfite, sodium formate, or sodium acetate, and the acid may be selected from phthalic acid, thiophthalic acid, formic acid, acetic acid, lactic acid, citric acid, succinic acid, adipic acid, boric acid, aliphatic dicarboxylic acids and mixtures thereof, hydrochloric acid, sulfuric acid, and ammonium salts thereof, and carbon dioxide. The proteolytic enzyme may be selected from a softening proteolytic enzyme.

[0044] The described deliming compositions can be realized in particular by using a deliming agent, whereby methods known to those skilled in the art for deliming hides and skins can be carried out, wherein only the deliming agent needs to be changed. In other words, methods known per se can be used, wherein the described graft polymer product is used as a deliming agent or wherein the deliming agent comprises the described graft polymer product.

[0045] The advantages of the described deliming compositions are, in particular, that the use of graft polymers based on natural polymers allows the use of ammonium salts in the deliming process to be avoided or reduced. The use of recycled raw materials and the reduction of ammonium salts in wastewaters offer significant ecological and economic advantages. When residual materials produced during tanning (e.g., hair and leather shavings) are used as starting materials for the graft polymers, this not only reduces the amount of waste but also provides logistical advantages for the tanning process.

[0046] Furthermore, the present invention makes it possible to lower the pH even in the cross section of the hide, without lowering the pH to or even below the isoelectric point. This prevents protein substances (possibly together with other dissolved particles) that entered the solution during the previous liming process from precipitating and settling on the surface of the hide in a difficult-to-remove form. Residues that render the hide surface unacceptable, especially during dyeing, and interfere with subsequent processing can thus be significantly reduced or even completely avoided. Furthermore, the feel of the resulting end product (leather) is not adversely affected.

[0047] By omitting ammonium salts according to the present invention, the deliming composition is thus free of such salts. Furthermore, the release of ammonia gas can be avoided, which, in addition to odor pollution, can also irritate the respiratory tract of the corresponding facility operators. Furthermore, the wastewater preferably contains no or only very small amounts of ammonia nitrogen derived from the skin, which further improves environmental protection. In other words, the corresponding ammonia nitrogen may be present in some cases, but only in very small amounts compared to deliming methods from the prior art.

[0048] Furthermore, the graft polymer is preferably dispersible or soluble in water, which can shape the process flow during deliming in a particularly advantageous manner.

[0049] All in all, this results in particular advantages from an ecological and economic point of view, which were not possible with the prior art.

[0050] Preferred water-soluble graft polymers can be obtained by homopolymerization or copolymerization of monomers A in the presence of natural substances B1) and / or B2). Suitable monomers A include (meth)acrylic acid of group (a) and its alkali metal salts, alkaline earth metal salts, or ammonium salts. Mixtures thereof can also be used. These salts can be obtained, for example, as (meth)acrylic acid when the acid is neutralized in aqueous solution with caustic soda, magnesium hydroxide solution, ammonia, amines, or alkaloid amines. Monomers A of group (a) can be graft copolymerized together with other monoethylenically unsaturated monomers (b) copolymerizable with monomers (a). The amount of monomer (a) in the monomer mixture is then 20 to 100% by weight, preferably 40 to 100% by weight, and in particular 98 to 100% by weight, relative to all monomers A, while monomer (b) can be contained in an amount of up to 80% by weight, preferably up to 60% by weight, and in particular up to 2% by weight.

[0051] Examples of monomers A of group (b) used in the graft polymerization are crotonic acid, maleic acid, maleic anhydride, fumaric acid, citraconic acid, citraconic anhydride, C1-C8 alkyl and hydroxyalkyl esters of acrylic acid, methacrylic acid or crotonic acid and mono- or di-C1-C8 alkyl or hydroxyalkyl esters of maleic acid, fumaric acid or citraconic acid, such as methyl acrylate, ethyl acrylate, n-butyl acrylate, methyl methacrylate, monomethyl maleate, dimethyl maleate, monoethyl maleate, diethyl maleate, β-hydroxyethyl acrylate, β- and γ-hydroxypropyl acrylate, δ-hydroxybutyl acrylate, β-hydroxyethyl methacrylate and β- and γ-hydroxypropyl methacrylate. Amides and N-substituted alkylamides of the compounds mentioned under (a) are also suitable as monomers A of group (b), for example acrylamide, methacrylamide, N-alkyl(meth)acrylamides, where the alkyl group has 1 to 18 carbon atoms, such as N-methylacrylamide, N,N-dimethylacrylamide, N-tert-butylacrylamide, N-octadecylacrylamide, dimethylaminopropylmethacrylamide, and acrylamidoglycolic acid. Other suitable monomers (b) are alkylaminoalkyl(meth)acrylates, for example β-(dimethylamino)ethyl methacrylate, β-(dimethylamino)ethyl acrylate, β-(diethylamino)ethyl acrylate, δ-(diethylamino)propyl acrylate, and δ-(diethylamino)propyl methacrylate.

[0052] Further suitable monomers from group (b) are monomers containing sulfonic acid groups, such as vinylsulfonic acid, allylsulfonic acid, methallylsulfonic acid, styrenesulfonic acid, 3-sulfopropyl acrylate, 3-sulfopropyl methacrylate and acrylamidopropanesulfonic acid, and monomers having phosphonic acid groups, such as vinylphosphonic acid, allylphosphonic acid and acrylamidomethylpropanesulfonic acid.

[0053] This group (b) of monomers A also includes N-vinylpyrrolidone, N-vinylcaprolactam, N-vinylformamide, N-vinyl-N-methylformamide, 1-vinylimidazole, 1-vinyl-2-methylimidazole, vinyl acetate and vinyl propionate, acrylonitrile and methacrylonitrile, acrolein and methacrolein, crotonaldehyde and its acetals.

[0054] Other suitable monomers A of group (b) are esters of alkoxylated C1-C8 alcohols with 2 to 50 mol of ethylene oxide, propylene oxide, butylene oxide or mixtures thereof reacted with monoethylenically unsaturated carboxylic acids of group (a), for example, esters of acrylic acid or methacrylic acid reacted with C1-C8 alcohols with different amounts of ethylene oxide (for example 3, 5, 7, 10 or 30 mol of ethylene oxide). 13 / 15 Esters of alcohols.

[0055] Also suitable as monomers A of group (b) are vinyl aromatic compounds, such as styrene and α-methylstyrene, as well as C1-C 12Olefins, such as ethylene, propylene, 1-butene, 2-butene or butadiene.

[0056] Other suitable monomers A of group (b) are the N-monosubstituted and N,N-disubstituted amides of monoethylenically unsaturated C3-C8 carboxylic acids, in which the amide nitrogen carries a polyoxyalkylated C2-C8 alkylene oxide which has been reacted with 2 to 100, in particular 3 to 20, mol of ethylene oxide, propylene oxide and / or butylene oxide. 28 Alkanols, especially C2-C 18 Alkanol as a substituent. An example of such a compound is H2C=CH-CO-NH-CH2CH2-O(C2H4O) n -H, H2C=CH-CO-N[CH2CH2O-(C2H4O) n -H]2, H2C=C(CH3)-CO-NH-(CH2)4-O-(C2H4O) n -H, H2C=C(CH3)-CO-NH-C2H4O-(C3H6) n -H and H2C=CH-CO-NH-(CH2) 18 -O-(C2H4O) n -H, wherein n=3 to 20 is applicable in the above compounds.

[0057] These basic monomers are preferably used in the form of salts with inorganic acids such as hydrochloric acid, sulfuric acid or nitric acid or in a quaternized form. Suitable quaternizing agents are, for example, dimethyl sulfate, diethyl sulfate, methyl chloride, ethyl chloride and benzyl chloride. Carboxylic acids are preferably used in the form of free acids and as alkali metal salts, alkaline earth metal salts or ammonium salts thereof or as mixtures thereof.

[0058] Component (b) of the monomer mixture A preferably used for preparing the graft polymer is crotonic acid, maleic acid, maleic anhydride, fumaric acid, citraconic acid, citraconic anhydride, C1-C8 alkyl, especially C1-C4 alkyl or hydroxyalkyl esters of acrylic acid or methacrylic acid or crotonic acid and mono- or di-C1-C8 alkyl, especially C1-C4 alkyl or hydroxyalkyl esters of maleic acid, fumaric acid or citraconic acid, acrylamide, methacrylamide, methacrolein, acrylamidomethylpropanesulfonic acid, N-vinylimidazole or mixtures thereof.

[0059] Graft polymerization product can be further modified in the presence of the monomer A of (c) group, by carrying out graft polymerization. In this case, the monomer mixture comprises a monomer with at least two ethylenically unsaturated non-conjugated double bonds in a molecule of especially up to 5 wt %. These compounds are conventionally used as crosslinking agents in copolymerization. These compounds can be added to the monomer of (a) group for copolymerization or to the monomer mixture formed by (a) and (b). If these compounds are used, the preferred amount of monomer (c) is 0.05 to 2 wt % relative to the total amount of monomers. When copolymerization, using the monomer A of (c) group simultaneously causes the K value of multipolymer to rise.

[0060] Correspondingly, it may be advantageous if the mixture of monomers (A) comprises:

[0061] (a) acrylic acid or methacrylic acid or a mixture thereof or an alkali metal salt, alkaline earth metal salt or ammonium salt thereof, and at least one of (b) and (c), wherein

[0062] (b) comprises other monoethylenically unsaturated monomers different from monomer (a) that are copolymerizable with monomer (a), and wherein

[0063] (c) A monomer having at least two ethylenically unsaturated non-conjugated double bonds in the molecule.

[0064] Suitable compounds (c) include, for example, methylenebisacrylamide, esters of acrylic acid and methacrylic acid with polyhydric alcohols (e.g., ethylene glycol diacrylate, glycerol triacrylate, ethylene glycol dimethacrylate, glycerol trimethacrylate), and polyols at least diestered with acrylic acid or methacrylic acid (e.g., pentaerythritol and glucose). Other suitable crosslinkers include divinylbenzene, divinyldioxane, pentaerythritol triallyl ether, and pentaallylsucrose. Water-soluble monomers from this group can preferably be used, in particular ethylene glycol diacrylate or ethylene glycol diacrylates of polyethylene glycols having a molecular weight of up to 3000 daltons, or mixtures thereof. In a preferred embodiment, to prepare the graft polymer, acrylic acid or its alkali metal, alkaline earth metal, or ammonium salts alone is used as monomer A, or a mixture of at least 80%, in particular at least 98%, by weight of acrylic acid or its alkali metal, alkaline earth metal, or ammonium salts and monomer (b) is used as monomer mixture A. The polymerization of monomer A is preferably carried out in the presence of a natural substance based on compound B1) or B2).

[0065] However, it may also be preferred that monomers A contain no monomers (b) and (c), or that monomers A consist only of monomers (a).

[0066] B1

[0067] Suitable polysaccharide derivatives are oxidatively, hydrolytically or enzymatically degraded polysaccharides, oxidatively hydrolytically degraded polysaccharides or oxidatively enzymatically degraded polysaccharides or chemically modified degradation products of these or chemically modified monosaccharides, oligosaccharides or polysaccharides.

[0068] From an economic point of view, starch, thermally and / or mechanically treated starch, oxidatively, hydrolytically or enzymatically degraded starch, and chemically modified starch are preferably used as the polysaccharide for the graft polymerization component B1). In particular, any starch is suitable. However, preference is given to using starch obtained from corn, wheat, rice, and cassava, and in particular potato starch. Starch is practically insoluble in water and can be converted into a water-soluble form in a known manner by thermal and / or mechanical treatment or by enzymatic or acid-catalyzed degradation. Another suitable component B1) is oxidatively degraded starch. Examples of starch degradation products obtainable by oxidative, hydrolytic, or enzymatic degradation of starch include the following compounds: dextrins such as white dextrin and yellow dextrin, maltodextrin, glucose syrup, maltose syrup, hydrolysis products with a high D-glucose content, and starch saccharification products such as maltose and D-glucose and their isomerization product, fructose.

[0069] Further suitable components B1) are oxidized starches such as dialdehyde starch and oxidized starch degradation products such as gluconic acid, glucaric acid and glucuronic acid. Such compounds are obtained, for example, by oxidizing starch with periodate, chromic acid, hydrogen peroxide, nitrogen dioxide, nitrogen tetroxide, nitric acid or perchloric acid.

[0070] Other suitable component B1) are chemically modified polysaccharides, especially chemically modified starches, such as starches and starch degradation products that have been converted into esters with acids and into ethers with alcohols. These substances can be esterified not only with inorganic acids but also with organic acids or their anhydrides or chlorides. In direct esterification, the water released leads to acid-catalyzed cleavage of the glucosidic bonds. Phosphorylated and acetylated starches and starch degradation products are particularly important industrially. The most common method for etherifying starch is to treat starch or starch degradation products with organic halides, epoxides, or sulfates in aqueous alkaline solution. Starch ethers include, for example, alkyl, hydroxyalkyl, carboxyalkyl, and allyl ethers of starch. Chemically modified starches in component B1) are particularly understood to include cationically modified starches, such as starches reacted with 2,3-glycidyltrimethylammonium chloride, as described in US Pat. No. 3,649,616.

[0071] Chemically modified polysaccharides include, for example, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethyl hydroxyethylene cellulose, sulfoethyl cellulose, carboxymethyl sulfoethyl cellulose, hydroxypropyl sulfoethyl cellulose, hydroxyethyl sulfoethyl cellulose, methyl sulfoethyl cellulose, and ethyl sulfoethyl cellulose.

[0072] Further suitable components B1) are chemically modified starch degradation products, for example hydrogenated products of starch hydrolysis, such as sorbitol and mannitol, maltitol and hydrogenated glucose syrups, or oxidatively hydrolytically or enzymatically degraded starches.

[0073] Also suitable are acid-catalyzed or enzymatic transglycosylation or glycosylation products such as methyl glucosides.

[0074] Particularly preferred components B1) are hydrolytically degraded starches, in particular wheat starches (eg starches with a high monosaccharide content), and pure monosaccharides.

[0075] In a preferred embodiment, the polysaccharide B1) has an average molecular weight of 500 to 10,000 daltons, in particular 3,000 to 10,000 daltons, preferably 3,000 to 8,000 daltons. Particularly preferably, the polysaccharide B1) is an oxidatively, hydrolytically or enzymatically degradable polysaccharide, in particular hydrolytically degraded starch, having an average molecular weight of 500 to 10,000 daltons, in particular 3,000 to 10,000 daltons, preferably 3,000 to 8,000 daltons.

[0076] Particularly preferred polysaccharides B1) are hydrolytically degraded starches from edible plants (such as potatoes or corn), especially with a broad molecular weight distribution. This can be achieved by mixing various hydrolytically degraded starches.

[0077] B2

[0078] Suitable polypeptide derivatives are hydrolytically or enzymatically degraded and, in some cases, chemically modified polypeptides.

[0079] In terms of polypeptide B2), preferably all proteins in which at least 20% by weight are dissolved in the polymerization medium under polymerization conditions. Examples of suitable proteins are given in Ullmann's Chemical Dictionary, 4th edition, Weinheim, 1980, Vol. 19, pp. 491 to 557. Polypeptides are renewable raw materials. They are, for example, from skin, support and connective tissue, bone and cartilage, such as collagen, elastin, gelatin, bone collagen and skin adhesives. Polypeptides from milk are milk polypeptides, casein and lactalbumin. Wool, bristles, feathers and hair provide keratin. Also suitable are polypeptides from fish and eggs and from blood as slaughterhouse waste, such as blood polypeptides, albumin, globulin, globin, fibrinogen and hemoglobin. In addition, suitable polypeptides are derived from plants, such as corn, wheat, barley, oats, such as gluten, prolamin, alcohol-soluble zein and effluent. Alternatively, the peptides can be obtained from seeds, such as soybeans, cottonseed, peanuts, sunflower, rapeseed, coconut, linseed, sesame, safflower, peas, soybeans, and lentils. Furthermore, polypeptide components from clover, alfalfa, grass, potato, cassava, and yam root can be used. Further polypeptide sources are bacteria, fungi, algae, and yeasts, such as Pseudomonas, Lactobacillus, penicillin, cyanobacteria, green algae, chlorella, spirulina, and residual yeast.

[0080] Preferred polypeptides for preparing the graft copolymer as component B2) are collagen (natural or modified by tanning) from skins and leathers, casein, gelatin, gluten, polypeptides from soybeans, cereals, especially wheat and corn, and peas. The polypeptides can be obtained from natural raw materials, for example, by dissolving, grinding, screening and sorting. In order to obtain them in a preferably soluble form, in many cases it is necessary to digest them by physical, chemical or enzymatic treatment, for example by acid or alkaline hydrolysis, fermentation with yeast, bacteria or enzymes, extraction methods for removing secondary components, coagulation from the extract by heating, addition of electrolytes, setting the pH or adding sedimentation agents. The pure product can be prepared, for example, by fractional dissolution and sedimentation or by dialysis.

[0081] Preferred polypeptides B2) have an average molecular weight of more than 1000 Dalton, in particular more than 3000 Dalton, and are preferably selected from the group consisting of animal polypeptides, plant polypeptides and hydrolysates thereof.

[0082] Such a molecular weight indicates that the hydrolyzate can be used according to the invention without setting a high degree of hydrolysis.

[0083] Particularly preferably, B2) comprises leather waste recycled by hydrolysis, protein extracts from defatted oilseeds (such as soybeans), milk proteins and vegetable proteins from wheat or corn.

[0084] It can also be preferably provided that the polypeptide comprises treated, for example alkaline or enzymatically treated, chrome-containing or chrome-free tanned cowhide shavings. From an ecological point of view, it is particularly meaningful to recycle chrome-containing shavings as residual substances produced during leather making. These shavings appear as fines during the setting of the thickness (the so-called splitting) in the leather making process, which mainly consist of collagen-containing material. If the leather is tanned beforehand with the aid of a chrome-containing tanning agent, the tanned leather (also known as wet blue leather) which is still wet with chrome generally contains, in addition to collagen, about 2 to 6% by weight of chromium in the oxidation state (III). Since chrome-containing tanning is the most widely used tanning method, a large amount of chrome-containing shavings waste is generated (about 17,000 tons per year in Germany alone). Separation into constituent components protein and chromium and the reuse of the chromium part, which can only be realized under high cost, makes the complete recycling of a large amount of waste material uneconomical usually, thereby the leather scraps are stored and disposed of as other garbage, pressed into leather fiber materials or burned under controlled conditions, but this causes environmental pollution. Common methods for separating protein and chromium include decomposing the leather scraps with acid or alkali and / or microbial or enzymatic degradation under heating, wherein these steps are combined with each other in a high cost, multi-step process. Through the acid hydrolysis of the leather scraps selected in EP3425069, it is necessary to pre-treat the chromium-containing material at high cost to remove all chromium from the initial material before hydrolysis. Therefore, the pre-treatment of the chromium-containing leather scraps lasts between 2-4 days. This makes the described process for the chromium-containing material highly costly and very time-consuming.

[0085] When using chrome-containing leather shavings, the possibility of alkaline hydrolysis and / or microbial or enzymatic degradation under heat eliminates the need for complex pretreatment of the chrome-containing leather shavings to separate the chromium and protein fractions. Since chromium becomes insoluble at pH values ​​> 4.5, the remaining solid chromium residues can be separated by simply filtering the liquid, protein-containing filtrate. The protein-containing filtrate can then be used as starting material for subsequent graft polymerization products, as described in WO 2012 / 163823 or DE 4416877.

[0086] Preparation process of grafted polymer

[0087] To prepare the graft polymer, monomer A is advantageously subjected to free radical polymerization in the presence of compounds of the sugar component B1) and / or the protein component B2). In some cases, it may be advantageous to use two or more of the compounds mentioned under B1) or two or more of the compounds mentioned under B2 for the effectiveness of the graft polymer obtained. For example, B1) may include mixtures of acid-catalyzed or enzymatically degraded starch and gluconic acid, mixtures of monosaccharides and oligosaccharides, mixtures of enzymatically degraded starch and monosaccharides, or mixtures of glucose and sucrose or mannose. For B2), mixtures of leather waste hydrolysate and vegetable protein from wheat or corn, mixtures of gelatin and milk protein, or mixtures of soy protein and feather hydrolysate may be mentioned. The polymerization can be carried out in the presence or absence of an inert solvent or inert diluent. Since polymerization in the absence of an inert solvent or diluent may in some cases result in an inhomogeneous graft polymer, it is preferred to carry out the graft polymerization in an inert solvent or diluent. Suitable are, for example, inert diluents in which the compounds mentioned under B1) or B2) can be suspended and in which the monomers A are dissolved, in which case the graft polymer product is present in suspension after the polymerization and can be easily isolated in solid form by filtration.

[0088] Suitable inert diluents are, for example, toluene, o-, m-, p-xylene and isomeric mixtures thereof, ethylbenzene, aliphatic hydrocarbons or gasoline fractions which do not contain polymerizable monomers. Chlorohydrocarbons such as chloroform, carbon tetrachloride, hexachloroethane, dichloroethane and tetrachloroethane are also suitable.

[0089] In the above-described process of suspending component B1) or B2) in an inert diluent, it is preferred to use anhydrous compounds of component B1) or B2), preferably anhydrides of the diacids from group (b) of monomer A. A preferred method for preparing the graft polymer is solution polymerization, in which the polysaccharide component B1) or B2), the monomers A, and the resulting graft copolymer are present at least in dispersed form and, in many cases, in dissolved form. Inert solvents such as water, methanol, ethanol, isopropanol, n-propanol, n-butanol, sec-butanol, tetrahydrofuran, dioxane, and mixtures thereof are suitable for solution polymerization.

[0090] The polymerization can be carried out continuously or batchwise. As already mentioned, components A and B1) or B2) can also be polymerized in the absence of an inert diluent or solvent. Continuous polymerization at temperatures between 160°C and 250°C is particularly suitable for this purpose. If desired, the polymerization can also be carried out in the absence of a polymerization initiator. However, it is preferred to also use a catalyst that forms free radicals under the polymerization conditions, such as inorganic and organic peroxides, persulfates, azo compounds, and redox catalysts. The described, preferably water-soluble graft polymers are generally prepared in the presence of a free radical initiator. Preferred free radical initiators are all compounds that have a half-life of less than 3 hours at the respectively selected polymerization temperature. If the polymerization is initially started at a lower temperature and concluded at a higher temperature, it is advantageous to carry out the reaction with at least two initiators that decompose at different temperatures, that is, to first start the polymerization with an initiator that decomposes at a lower temperature and then to conclude the main polymerization reaction with an initiator that decomposes at a higher temperature. Water-soluble and water-insoluble initiators, or mixtures of water-soluble and water-insoluble initiators, can be used. The water-insoluble initiator can then be dissolved in the organic phase.

[0091] The following initiators can be used advantageously for temperatures of 40° C. to 60° C.: acetylcyclohexanesulfonyl peroxide, diacetyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, bis-2-ethylhexyl peroxydicarbonate, tert-butyl perneodecanoate, 2,2′-phenylpropionamidine dihydrochloride, 2,2′-azobis(2-methylpropionamidine) dihydrochloride. The following initiators can be used advantageously for temperatures of 60° C. to 80° C.: tert-butyl perpivalate, dioctanoyl peroxide, dilauroyl peroxide, 2,2′-azobis(2,4-,5-dimethylvaleronitrile).

[0092] For temperatures of 80 to 100° C., the following initiators can advantageously be used: dibenzoyl peroxide, tert-butyl per-2-ethylhexanoate, tert-butyl permaleate, 2,2′-azobisisobutyronitrile, dimethyl 2,2′-azobisisobutyrate, sodium persulfate, potassium persulfate, ammonium persulfate.

[0093] For temperatures between 100° C. and 120° C., the following initiators can be used advantageously: bis(tert-butylperoxy)cyclohexane, tert-butylperoxyisopropylcarbonic acid, tert-butyl peroxyacetate, hydrogen peroxide.

[0094] For temperatures between 120° C. and 140° C., the following initiators can be used advantageously: 2,2-bis(tert-butylperoxy)butane, dicumyl peroxide, di-tert-amyl peroxide, di-tert-5-butyl peroxide.

[0095] For temperatures above 140°C, the following initiators can be advantageously used: p-menthane hydroperoxide, pinane hydroperoxide, cumene hydroperoxide, and tert-butyl hydroperoxide. In addition to the aforementioned initiators, salts or complexes of heavy metals, such as copper, cobalt, manganese, iron, vanadium, cerium, nickel, and chromium salts, or organic compounds such as benzoin, dimethylaniline, or ascorbic acid, can be used as grafting agents, either alone or as adjuvants for free radical initiators. When used together with free radical initiators, the half-life of the aforementioned free radical initiators can be reduced. For example, tert-butyl hydroperoxide can be activated by adding 5 ppm of copper(II) acetylacetonate, allowing polymerization to proceed at 100°C. The reducing component of the redox catalyst can also be provided by, for example, sodium sulfite, sodium bisulfite, sodium formaldehyde sulfoxylate, and hydrazine.

[0096] Preferably, 0.01 to 20% by weight, preferably 0.05 to 15% by weight, of a polymerization initiator or a mixture of polymerization initiators, a free radical initiator, or a heavy metal-based grafting agent is used, relative to the monomers A used in the polymerization. A reducing compound is added as a redox component in an amount of 0.01 to 30% by weight, relative to the monomers A used in the polymerization, and a heavy metal is used in an amount of 0.1 to 100 ppm, preferably 0.5 to 10 ppm, relative to the monomers A used in the polymerization. It is also advantageous to use a combination of a peroxide, a reducing agent, and a heavy metal as a redox catalyst.

[0097] The polymerization of monomer A can also be carried out under the action of ultraviolet radiation, with or without a UV initiator. Conventional photoinitiators or sensitizers are used for polymerization under the action of UV radiation. These include, for example, compounds such as benzoin and benzoin ethers, α-methylbenzoin, and α-phenylbenzoin. Triplet sensitizers such as benzyl diketal can also be used. In addition to high-energy UV lamps such as carbon arc lamps, mercury vapor lamps, or xenon lamps, low-UV light sources such as phosphor tubes with a high proportion of blue light can be used as UV radiation sources.

[0098] A preferred method according to the invention for preparing graft polymers using component B1) or B2) as a core is a free-radical-induced copolymerization, in which the components of the monomers of A) are added to B1) or B2) in an inert solvent at a temperature of 40° C. to 180° C. in the presence of a free-radical-forming initiator, characterized in that at least 50% by weight, in particular more than 70% by weight, of the free-radical-forming initiator is present with component B1) or B2) before the addition of the monomers A), and the remaining initiator is added together with the monomers of A) or afterwards.

[0099] The remainder of the initiator is preferably added to the reaction mixture together with the monomers from A).

[0100] During graft polymerization, a polymerization regulator can be used to regulate the side chain length as required. Any compound containing active hydrogen can be used as a chain transfer agent. Suitable regulators are, for example, mercapto compounds such as mercapto alcohols, mercapto acids or mercapto esters. Suitable regulators in addition are allyl alcohol, aldehydes, formic acid, amines or their salts. When necessary, 0.05-10 wt % relative to the amount of monomer A can be used.

[0101] Other conditions for the graft polymerization follow conventional methods for this type of process. The polymerization system should be under an inert gas atmosphere that excludes oxygen from the air. Water-soluble phosphorus compounds with oxidation states 1-4 can be used to reduce the color of the resulting graft polymer, while temperature and product uniformity can be controlled by proper mixing and limiting the addition rate of monomer mixture A.

[0102] As already mentioned, the polysaccharide B1) can also be subjected to graft polymerization in aqueous suspension. However, the graft polymerization product is preferably prepared from the polysaccharide by first converting the water-insoluble polysaccharide in the aqueous suspension into a water-soluble form with the addition of enzymes and / or acids and subjecting the resulting aqueous solution of the degraded polysaccharide to graft polymerization. In this case, a water-insoluble polysaccharide, such as potato starch, is first suspended in water and degraded. This degradation can be carried out in a known manner under the action of enzymes such as α- or β-amylases or under the action of debranching enzymes such as pullulanase or by the action of inorganic or organic acids. Examples of suitable inorganic acids are phosphoric acid, sulfuric acid, hydrochloric acid and nitric acid. Examples of suitable organic acids are saturated or unsaturated carboxylic acids, such as formic acid, acetic acid, propionic acid, acrylic acid, methacrylic acid, maleic acid, itaconic acid, p-toluenesulfonic acid and benzenesulfonic acid.

[0103] The enzymatic degradation of starch is carried out at 30° C. to 120° C., and the hydrolytic degradation of starch is carried out at 50° C. to 150° C. The hydrolytic degradation takes about 5 minutes to 10 hours, wherein the extent of the hydrolytic degradation of starch depends on the selected temperature, pH value and time.

[0104] The temperature during the graft polymerization is generally between 40°C and 180°C, preferably between 60°C and 150°C. The polymerization is carried out under pressure as soon as the polymerization temperature is above the boiling point of the inert diluent or solvent or monomer A. During the polymerization in the presence of an inert solvent or inert diluent, the concentration of components A and B1) or B2) is 10 to 80% by weight, preferably 20 to 70% by weight.

[0105] The preparation of the graft polymer product can be carried out in conventional polymerization equipment. For example, stirred tanks equipped with anchor, paddle, or blade stirrers or multi-stage pulsed convection stirrers are used for this purpose. In particular, when graft polymerization is carried out in the absence of a diluent, it may be advantageous to carry out the polymerization in a kneader. It may also be necessary to carry out the polymerization in a kneader when the process is carried out at high concentrations or when the natural substance has a high molecular weight and initially swells significantly.

[0106] In a preferred embodiment, the graft polymer can be obtained by free radical polymerization of acrylic acid, a polypeptide hydrolyzate, and a polysaccharide hydrolyzate. For example, the monomer mixture used to prepare the graft polymer can consist of acrylic acid, a polypeptide hydrolyzate, and a polysaccharide hydrolyzate, i.e., it does not contain other monomers.

[0107] The aqueous graft polymer solutions or dispersions obtained according to the process of the invention can be used directly as deliming agents in the preparation of leather and hides. However, they can also contain other additives and be dried, for example, by spray drying with or without other additives.

[0108] The graft polymer products that can be prepared according to the method described above are colorless to brown products. In the case of polymerization in an aqueous medium, the product exists in the form of a dispersion or polymer solution. Depending on the respective composition or concentration of the graft polymer product, the product is an aqueous solution or dispersion with a low viscosity to a paste. Due to the content of natural substances, the graft polymer products described can be more biodegradable than the polymers based on ethylenically unsaturated monomers used previously, but can at least be disposed of together with sewage sludge from wastewater treatment facilities.

[0109] The aqueous graft polymer solutions obtainable in this way are very suitable as deliming agents for the preparation of leather and hides.

[0110] The graft polymers according to the invention can then be used for deliming hides and skins in aqueous tanning liquors. For these applications, graft polymers consisting solely of acrylic acid or its salts or of a monomer mixture A of acrylic acid or its salts (a) and monomers (b) with at least 80% by weight, in particular at least 98% by weight, of (a) are particularly advantageous.

[0111] Basically it may be preferred that the graft polymer product is obtainable by free radical polymerization of:

[0112] A) A monomer selected from the following monomers or a mixture of the following monomers

[0113] (a) 20 to 100 weight parts, relative to monomer A, of acrylic acid or methacrylic acid or a mixture thereof or an alkali metal salt, alkaline earth metal salt or ammonium salt thereof,

[0114] (b) 0 to 80% by weight, relative to monomer A, of other monoethylenically unsaturated monomers copolymerizable with monomer (a), and

[0115] (c) 0 to 5% by weight, relative to monomer A, of monomers having at least two ethylenically unsaturated, non-conjugated double bonds in the molecule, in the presence of at least one of the following:

[0116] B1) polysaccharides, oxidatively, hydrolytically or enzymatically degraded polysaccharides, oxidatively hydrolytically degraded polysaccharides or oxidatively enzymatically degraded polysaccharides or chemically modified degradation products of these, chemically modified monosaccharides, oligosaccharides or polysaccharides or mixtures of the compounds given, and

[0117] B2) Polypeptides, hydrolytically or enzymatically degraded and optionally chemically modified polypeptides or mixtures of the given compounds, preferably in a weight ratio A:(B1+B2) of 60:40 to 1:99.

[0118] For further advantages and technical features of the deliming composition, reference is made to the embodiments relating to the deliming method, the method for leather making, its use and the examples, and vice versa.

[0119] Furthermore, a deliming method for deliming hides and skins to be delimed is described, wherein the deliming comprises, in particular, lowering the pH value of the hides and skins to be delimed. The method is characterized in that it comprises at least the following method steps:

[0120] a) providing hides and skins to be delimed; and

[0121] b) mixing the hides and skins to be delimed with a deliming agent, wherein the deliming agent has a graft polymerisation product of at least one of a polysaccharide, a polypeptide or a derivative thereof, wherein the derivative of the polysaccharide is an oxidatively, hydrolytically or enzymatically degradable polysaccharide, an oxidized hydrolytically degraded polysaccharide or an oxidized enzymatically degraded polysaccharide or a chemically modified degradation product of such a polysaccharide, an oligosaccharide or a chemically modified monosaccharide, an oligosaccharide or a polysaccharide, and wherein the derivative of the polypeptide is a hydrolytically or enzymatically degraded and optionally chemically modified polypeptide, the graft polymerisation product being obtainable by free radical polymerisation of

[0122] A) A monomer selected from the following monomers or a mixture of the following monomers

[0123] (a) acrylic acid or methacrylic acid or a mixture thereof or an alkali metal salt, alkaline earth metal salt or ammonium salt thereof, and optionally at least one of (b) and (c), wherein

[0124] (b) comprises other monoethylenically unsaturated monomers copolymerizable with monomer (a), and wherein

[0125] (c) a monomer having at least two ethylenically unsaturated non-conjugated double bonds in the molecule,

[0126] If at least one of the following exists:

[0127] B1) polysaccharides, oxidatively, hydrolytically or enzymatically degraded polysaccharides, oxidatively hydrolytically degraded polysaccharides or oxidatively enzymatically degraded polysaccharides or chemically modified degradation products of these, chemically modified monosaccharides, oligosaccharides or polysaccharides or mixtures of the compounds given, and

[0128] B2) Polypeptides, hydrolytically or enzymatically degraded and optionally chemically modified polypeptides or mixtures of the given compounds.

[0129] Such a method is therefore a deliming method, in which liming substances are to be removed from hides, in particular previously limed, and in which the pH value of the hides is to be lowered, in particular, to a substantially neutral range, in particular to a range of 7 to 9. Hides to be delimed are therefore to be understood as meaning hides having a pH value in the alkaline range, in particular in a pH range of greater than 9, in particular greater than or equal to 10, for example greater than or equal to 11.

[0130] The method on which the invention is based corresponds in particular to the method known to the person skilled in the art for deliming hides and skins, wherein, however, the described graft polymer products are used as deliming agents.

[0131] The method may include, in a first step, so-called pre-liming using buffer salts and / or acids. However, it is also possible to omit the so-called pre-liming. The described method then comprises, for example, the following steps: a) washing the provided hides to be delimed with water and draining the water again, followed by the addition of water, sodium bisulfite, and a deliming agent consisting of an organic acid; b) adding a deliming agent based on a graft polymer and, optionally but not necessarily, a small amount of ammonium salt, and monitoring the pH value during the process; c) ending the process as soon as a cross-section of the hide no longer shows color with phenolphthalein.

[0132] The advantages of the described method are therefore particularly that, by using graft polymers based on natural polymers, the use of ammonium salts in the deliming process can be avoided or reduced. The use of recycled raw materials and the reduction of ammonium salts in wastewaters offer significant ecological and economic advantages. When residual materials produced during tanning (e.g., hair and leather shavings) are used as starting materials for the graft polymers, this not only reduces the amount of waste but also provides logistical advantages for the tanning process.

[0133] In method step b), the deliming agent can preferably be added in a proportion of ≥0.5% by weight to ≤12% by weight, preferably ≥1.5% by weight to ≤8% by weight, for example ≥2% by weight to ≤6% by weight, preferably ≥2.5% by weight to ≤5% by weight, relative to the amount of limed hides. It has been shown that only such a proportion of the deliming agent can be used effectively for deliming without simultaneously causing significant local changes in the pH value. In particular, the undesirable local pH drop into a very acidic range, as described above, can be prevented.

[0134] For further advantages and technical features of the deliming process reference is made to the embodiments relating to the deliming composition, the process for leather making, the use thereof and the examples, and vice versa.

[0135] A tanning method is also described, having the following method steps:

[0136] i) providing hides and skins;

[0137] ii) liming or dehairing the hide;

[0138] iii) deliming the hide; and

[0139] iv) tanning the hide,

[0140] The method is characterized in that the deliming of the hide according to method step iii) is carried out using a deliming agent, which comprises a graft polymer product of at least one of a polysaccharide, a polypeptide or a derivative thereof, wherein the derivative of the polysaccharide is an oxidatively, hydrolytically or enzymatically degradable polysaccharide, an oxidized hydrolytically degraded polysaccharide or an oxidized enzymatically degraded polysaccharide or a chemically modified degradation product of such a polysaccharide, an oligosaccharide or a chemically modified monosaccharide, an oligosaccharide or a polysaccharide, and wherein the derivative of the polypeptide is a hydrolytically or enzymatically degraded and optionally chemically modified polypeptide, the graft polymer product being obtainable by free radical polymerization of

[0141] A) A monomer selected from the following monomers or a mixture of the following monomers

[0142] (a) acrylic acid or methacrylic acid or a mixture thereof or an alkali metal salt, alkaline earth metal salt or ammonium salt thereof, and optionally at least one of (b) and (c), wherein

[0143] (b) comprises other monoethylenically unsaturated monomers different from monomer (a) that are copolymerizable with monomer (a), and wherein

[0144] (c) comprising monomers having at least two ethylenically unsaturated non-conjugated double bonds in the molecule,

[0145] If at least one of the following exists:

[0146] B1) polysaccharides, oxidatively, hydrolytically or enzymatically degraded polysaccharides, oxidatively hydrolytically degraded polysaccharides or oxidatively enzymatically degraded polysaccharides or chemically modified degradation products of these, chemically modified monosaccharides, oligosaccharides or polysaccharides or mixtures of the compounds given, and

[0147] B2) Polypeptides, hydrolytically or enzymatically degraded and optionally chemically modified polypeptides or mixtures of the given compounds.

[0148] The method can also include process steps that are generally known to those skilled in the art in the field of leather making without departing from the scope of the present invention. Examples of such other optional process steps include, for example, softening, breaking, soaking, creasing, dyeing, and drying, without being limited thereto. These steps can also be carried out in a manner known to those skilled in the art.

[0149] As described above, significant advantages from an ecological and economic point of view can be achieved by using deliming agents.

[0150] The other process steps described, such as in particular liming or tanning, can otherwise be carried out in principle in a manner known per se.

[0151] Liming of hides and skins for dehairing and swelling (e.g., to remove undesirable proteins) within the tanning industry is carried out, in particular, in an alkaline medium, usually with the aid of inorganic or organic sulfides, at a pH of 12 or higher. Lime is usually used as the alkaline medium, usually alone, but sometimes also in admixture with caustic soda or soda. However, liming is generally known to those skilled in the art.

[0152] Deliming then takes place as described above.

[0153] Tanning can then take place after deliming.

[0154] Tanning can also be carried out in a manner known to those skilled in the art. Basically, in a known manner, tanning is understood to be the preservative treatment of animal skins with or without hair by means of a tanning agent. During tanning, the tanning agent is chemically connected to the fibrous tissue of the animal skin, which chemically connects to prevent the hardening and slaking of the fibrous tissue of the skin and to stabilize or protect the animal skin from oxidation or corruption. At this, the method described here can include any type of tanning. Exemplary tanning, for example, includes using 33% basic chromium sulfate with a chromium (III) oxide content of approximately 26% when chromium-containing tanning. The advantage is that using chromium (III) salts is considered to be harmful to health and does not cause difficulties in shoes or clothing areas even under high-intensity skin contact for the vast majority of people.

[0155] In particular, the tanning can be carried out without graft polymers, as described above with respect to the deliming method or deliming composition. However, it can also be provided that the tanning is carried out with the above-mentioned graft polymers.

[0156] For further advantages and technical features of the leather making process reference is made to the embodiments relating to the deliming composition, the deliming process, the use thereof and the examples, and vice versa.

[0157] According to the above, the present invention also provides the use of the above-described graft polymer product and thereby, for example, a deliming composition as described above and / or a deliming method as described above for deliming hides and skins.

[0158] Such use offers significant advantages from an ecological and economical perspective.

[0159] For further advantages and technical features of use reference is made to the embodiments relating to the deliming composition, the method for leather making, the deliming method and the examples, and vice versa.

[0160] According to the above, the present invention also provides leather and semi-finished products of the leather-making process, which have been delimed with a graft polymer. The graft polymer is characterized in that it is a graft polymerization product of at least one of a polysaccharide, a polypeptide or a derivative thereof, wherein the polysaccharide derivative is an oxidatively, hydrolytically or enzymatically degradable polysaccharide, an oxidized hydrolytically degraded polysaccharide or an oxidized enzymatically degraded polysaccharide or a chemically modified degradation product of such a polysaccharide, an oligosaccharide or a chemically modified monosaccharide, an oligosaccharide or a polysaccharide, and wherein the polypeptide derivative is a hydrolytically or enzymatically degraded and optionally chemically modified polypeptide.

[0161] The graft polymer product can be obtained by free radical polymerization of:

[0162] A) A monomer selected from the following monomers or a mixture of the following monomers

[0163] (a) acrylic acid or methacrylic acid or a mixture thereof or an alkali metal salt, alkaline earth metal salt or ammonium salt thereof, and optionally at least one of (b) and (c), wherein

[0164] (b) comprises other monoethylenically unsaturated monomers different from monomer (a) that are copolymerizable with monomer (a), and wherein

[0165] (c) comprising monomers having at least two ethylenically unsaturated non-conjugated double bonds in the molecule,

[0166] If at least one of the following exists:

[0167] B1) polysaccharides, oxidatively, hydrolytically or enzymatically degraded polysaccharides, oxidatively hydrolytically degraded polysaccharides or oxidatively enzymatically degraded polysaccharides or chemically modified degradation products of these, chemically modified monosaccharides, oligosaccharides or polysaccharides or mixtures of the compounds given, and

[0168] B2) Polypeptides, hydrolytically or enzymatically degraded and optionally chemically modified polypeptides or mixtures of the given compounds.

[0169] Such leather or such semi-finished products of the tanning process offer considerable advantages from an ecological and economical perspective with regard to their production.

[0170] The semi-finished product can in particular be a semi-finished product which is directly produced by deliming and has not yet been tanned. For example, the delimed and not yet tanned semi-finished product can be placed in a solution comprising the graft polymer.

[0171] The leather may be manufactured leather.

[0172] For further advantages and technical features of the leather and semi-finished products, reference is made to the embodiments relating to the use, the deliming composition, the method for leather making, the deliming method and the examples, and vice versa. Example

[0173] The invention is explained in more detail with the aid of the following examples, without being restricted thereby.

[0174] Preparation of grafted polymer products

[0175] The protein hydrolysate used in the following examples was derived from a commercial facility for alkaline treatment of chrome-containing or chrome-free tanned cattle hide shavings, wherein in the first case a chrome-containing protein hydrolysate was produced and in the second case a chrome-free protein hydrolysate was produced. In the case of the chrome-containing protein hydrolysate, the protein hydrolysate was filtered prior to use to separate the solid chromium residue from the liquid, protein-containing filtrate. (The protein hydrolysate may have an average molecular weight between about 1000 and 8000 daltons, preferably between 2000 and 3000 daltons.)

[0176] The starch hydrolysate used was also sourced from a commercial facility used for alkaline / enzymatic treatment of wheat flour. (The starch hydrolysate had a molecular weight of approximately 3,000 Daltons.)

[0177] The advantage of such a molecular weight is especially the possible lower degree of hydrolysis.

[0178] General process of graft polymerization

[0179] 40% by weight of the protein hydrolysate and 40% by weight of the starch hydrolysate were placed in a 1-liter reactor. The reactor contents were heated to 88-92°C with stirring, and the corresponding amount of hydrogen peroxide (30%, q. 1) was added to the mixture and stirred for 15 minutes. Subsequently, an aqueous solution of ammonium persulfate (10%), the corresponding amount of 70% acrylic acid (prepared by diluting 98% acrylic acid with the corresponding amount of water), and the corresponding amount of hydrogen peroxide (30%, q. 2) were added. After a reaction time of 30 minutes, hydrogen peroxide (30%, q. 3) was added again, and stirring was continued for 2 hours until the temperature reached 88-92°C. After the reactor contents had cooled to 40°C, 50% sodium hydroxide solution was slowly added with stirring, ensuring that the reactor temperature remained below 60°C, until a pH of 4-5 was achieved. The final product was obtained by cooling the reactor to room temperature with stirring, adding the biocide, and mixing thoroughly.

[0180] P1) Graft polymer 1

[0181] According to the general process of graft polymerization 1

[0182]

[0183] P2) Graft polymer 2

[0184] According to the general process of graft polymerization

[0185]

[0186] P3) Graft polymer 3

[0187] According to the general process of graft polymerization

[0188]

[0189] P4) Graft polymer 4

[0190] According to the general process of graft polymerization

[0191]

[0192] P5) Graft polymer 5

[0193] According to the general process of graft polymerization 1

[0194]

[0195] P6) Graft polymer 6

[0196] According to the general process of graft polymerization 1

[0197] Material Amount [g] Protein hydrolysates 156.1 starch hydrolysates 565.3 Hydrogen peroxide (amount 1) 0.5 Ammonium persulfate solution 3 acrylic acid 21.3 Hydrogen peroxide (amount 2) 1.0 Hydrogen peroxide (3 qt) 1.0

[0198] Application example using graft polymer products

[0199] Application Example 1: Ammonium-free deliming agent with grafted polymer product 1

[0200] Bare hides (cow hides) broken and weighed after liming were used as starting material, with a thickness of approximately 3.5 mm. All chemical amounts below refer to this reference weight (bare hide weight).

[0201] The limed hides were washed with 150% water according to the usual preparations known to those skilled in the art. Subsequently, 30% water, 0.3% sodium bisulfite, and 0.3% Peltec DL (a dicarboxylic acid mixture, a commercial product from Lanxess) were added. After 15 minutes, 5% of the grafted polymer from Example 1 was added and allowed to react until a cross-section of the hide showed no more color using the pH indicator phenolphthalein (pH < 8.2). Table 1 shows the process steps of the method according to the invention and the subsequent soaking and tanning steps for producing semi-finished leather products (weight % relative to the weight of the hide).

[0202] Table 1:

[0203]

[0204]

[0205] After the method of the invention, the semi-finished leather product is placed on a base, drooped and folded and then further processed into finished crust leather according to conventional methods. This crust leather is then qualitatively evaluated.

[0206] Application Example 2: Ammonium-free deliming agent with grafted polymer product 2

[0207] Same as Example 1, except that 5% of the grafted polymer 2

[0208] Application Example 3: Ammonium-reducing deashing agent with grafted polymer product 3

[0209] Same as Example 1, except that 0.5% of Peltec DLA (a mixture of ammonium salts, a commercial product of Lanxess AG) was added before adding 2.5% of the graft polymer 3.

[0210] Application Example 4: Ammonium-reducing deashing agent with grafted polymer product 4

[0211] Same as Example 1, except that 0.5% of Peltec DLA (a mixture of ammonium salts, a commercial product of Lanxess) was added before adding 2.5% of the graft polymer 4.

[0212] Application Example 5: Ammonium-reducing deashing agent with grafted polymer product 5

[0213] Same as Example 1, except that 0.5% of Peltec DLA (a mixture of ammonium salts, a commercial product of Lanxess) was added before adding 2.5% of the graft polymer 5.

[0214] Application Example 6: Ammonium-reducing deashing agent with grafted polymer product 6

[0215] Same as Example 1, except that 0.5% of Peltec DLA (a mixture of ammonium salts, a commercial product of Lanxess) was added before adding 2.5% of the graft polymer 6.

[0216] Comparative Example 1: Deliming agent with ammonium salt

[0217] Same as Example 1, except that 2.0% of Peltec DLA (a mixture of ammonium salts, a commercial product of Lanxess) was added to the grafted polymer product.

[0218] Table 2:

[0219]

[0220] As shown in Table 2, when deliming with the graft polymer alone or with a reduced amount of ammonium salt compared to the comparative example, pH values ​​comparable to those of the comparative example, when deliming with ammonium salt alone, were achieved after 60 minutes at the latest. Although the pH values ​​after 30 minutes were slightly lower in some cases, they were still well below the avoidable pH value of approximately 5 (isoelectric point of protein) and the associated quality problems of the finished crust leather. This demonstrates the excellent buffering effect of these substances. The similar pH value of approximately 8.5 at the end of the process indicates that the graft polymer neutralizes the leather cross section just as well as the ammonium salt.

[0221] In any case, when the graft polymer products are used, the ammonium nitrogen values ​​in the wastewater are significantly reduced, whether in the ammonium salt-free or reduced ammonium salt process.

[0222] The value of approximately 4300 ppm in the deliming process with ammonium salts was reduced to a value of approximately 200 ppm in the process without ammonium salts and to approximately 1000 ppm in the process with reduced ammonium salts. This means that, compared to the deliming process with ammonium salts, the ammonium content in the wastewater was reduced by 95% in the first case and by 75% in the second case.

[0223] In the case of the ammonium salt-free method, the penetration time is slightly longer than in the deliming method containing ammonium salt, but it is still within acceptable levels for professionals. By using significantly reduced amounts of ammonium salt and graft polymer simultaneously, the treatment time becomes consistent. This can be seen in Examples 3-6.

[0224] All the crust leathers obtained from the hides obtained in Examples 1 to 6 had a homogeneous colour, a soft hand and a very fine grain comparable to that of the comparative example.

Claims

1. A deliming composition for deliming leather, characterized in that The deliming composition has at least: - hides and skins to be delimed; and - a deliming agent, wherein the deliming agent has a graft polymerization product of at least one of a polysaccharide, a polypeptide or a derivative thereof, wherein the derivative of the polysaccharide is an oxidatively, hydrolytically or enzymatically degraded polysaccharide, an oxidized hydrolytically degraded polysaccharide or an oxidized enzymatically degraded polysaccharide or such chemically modified degradation products or chemically modified monosaccharides, oligosaccharides or polysaccharides, and wherein the derivative of the polypeptide is a hydrolytically or enzymatically degraded and optionally chemically modified polypeptide, wherein the graft polymer product is obtained by free radical polymerization of: A) A monomer selected from the following monomers or a mixture of the following monomers (a) acrylic acid or methacrylic acid or a mixture thereof or an alkali metal salt, alkaline earth metal salt or ammonium salt thereof, and optionally at least one of (b) and (c), wherein (b) comprises other monoethylenically unsaturated monomers copolymerizable with monomer (a) and different from monomer (a), and wherein (c) comprising monomers having at least two ethylenically unsaturated non-conjugated double bonds in the molecule, If at least one of the following exists: B1) polysaccharides, oxidatively, hydrolytically or enzymatically degraded polysaccharides, oxidatively hydrolytically degraded polysaccharides or oxidatively enzymatically degraded polysaccharides or chemically modified degradation products of these, chemically modified monosaccharides, oligosaccharides or polysaccharides or mixtures of the compounds given, and B2) Polypeptides, hydrolytically or enzymatically degraded and optionally chemically modified polypeptides or mixtures of the given compounds.

2. The deliming composition according to claim 1, characterized in that The monomer A does not contain monomers (b) and (c).

3. The deliming composition according to claim 1, characterized in that The monomer mixture of the monomer (A) comprises: (a) acrylic acid or methacrylic acid or a mixture thereof or an alkali metal salt, alkaline earth metal salt or ammonium salt thereof, and at least one of (b) and (c), wherein (b) comprises other monoethylenically unsaturated monomers copolymerizable with monomer (a) and different from monomer (a), and wherein (c) includes monomers having at least two ethylenically unsaturated non-conjugated double bonds in the molecule.

4. The deliming composition according to any one of claims 1 to 3, characterized in that The graft polymer product is obtained by free radical polymerization of: A) A monomer selected from the following monomers or a mixture of the following monomers (a) 20 to 100% by weight, relative to monomer A, of acrylic acid or methacrylic acid or a mixture thereof or an alkali metal salt, alkaline earth metal salt or ammonium salt thereof, (b) 0 to 80% by weight, relative to monomer A, of other monoethylenically unsaturated monomers copolymerizable with monomer (a), and (c) 0 to 5% by weight, relative to monomer A, of monomers having at least two ethylenically unsaturated, non-conjugated double bonds in the molecule, in the presence of at least one of the following: B1) polysaccharides, oxidatively, hydrolytically or enzymatically degraded polysaccharides, oxidatively hydrolytically degraded polysaccharides or oxidatively enzymatically degraded polysaccharides or chemically modified degradation products of these, chemically modified monosaccharides, oligosaccharides or polysaccharides or mixtures of the compounds given, and B2) Polypeptides, hydrolytically or enzymatically degraded and optionally chemically modified polypeptides or mixtures of the given compounds.

5. The deliming composition according to any one of claims 1 to 3, characterized in that The graft polymer product is obtained through free radical polymerization of acrylic acid, polypeptide hydrolyzate and polysaccharide hydrolyzate.

6. The deliming composition according to any one of claims 1 to 3, characterized in that The polysaccharide B1) has an average molecular weight in the range of 500-10 000 Daltons.

7. The deliming composition according to any one of claims 1 to 3, characterized in that The polysaccharide B1) has an average molecular weight in the range of 3000-10000 Daltons.

8. The deliming composition according to any one of claims 1 to 3, characterized in that The polysaccharide B1) comprises hydrolytically degraded starch.

9. The deliming composition according to any one of claims 1 to 3, characterized in that Said polypeptide B2) has an average molecular weight in the range of greater than or equal to 1000 Daltons.

10. The deliming composition according to any one of claims 1 to 3, characterized in that Said polypeptide B2) has an average molecular weight in the range of greater than or equal to 3000 Daltons.

11. The deliming composition according to any one of claims 1 to 3, characterized in that The polypeptides B2) comprise treated shavings of chrome-containing or chrome-free tanned cowhide.

12. A deliming method for deliming hides and skins to be delimed, characterized in that The deliming method comprises at least the following steps: a) providing hides and skins to be delimed; and b) mixing the hides and skins to be delimed with a deliming agent, wherein the deliming agent comprises a graft polymerization product of at least one of a polysaccharide, a polypeptide or a derivative thereof, wherein the derivative of the polysaccharide is an oxidatively, hydrolytically or enzymatically degradable polysaccharide, an oxidized hydrolytically degraded polysaccharide or an oxidized enzymatically degraded polysaccharide or a chemically modified degradation product of such a polysaccharide or a chemically modified monosaccharide, oligosaccharide or polysaccharide, and wherein the derivative of the polypeptide is a hydrolytically or enzymatically degraded and optionally chemically modified polypeptide, wherein the graft polymer product is obtained by free radical polymerization of: A) A monomer selected from the following monomers or a mixture of the following monomers (a) acrylic acid or methacrylic acid or a mixture thereof or an alkali metal salt, alkaline earth metal salt or ammonium salt thereof, and optionally at least one of (b) and (c), wherein (b) comprises other monoethylenically unsaturated monomers copolymerizable with monomer (a) and different from monomer (a), and wherein (c) comprising monomers having at least two ethylenically unsaturated non-conjugated double bonds in the molecule, If at least one of the following exists: B1) polysaccharides, oxidatively, hydrolytically or enzymatically degraded polysaccharides, oxidatively hydrolytically degraded polysaccharides or oxidatively enzymatically degraded polysaccharides or chemically modified degradation products of these, chemically modified monosaccharides, oligosaccharides or polysaccharides or mixtures of the compounds given, and B2) Polypeptides, hydrolytically or enzymatically degraded and optionally chemically modified polypeptides or mixtures of the given compounds.

13. The deliming method according to claim 12, characterized in that In process step b), the deliming agent is present in a proportion of ≥0.5% by weight to ≤12% by weight relative to the amount of hides and skins to be delimed.

14. A method for making leather, comprising the following steps: i) providing hides and skins; ii) liming or dehairing the hide; iii) deliming the hide; and iv) tanning the hide, It is characterized by: deliming the hide according to method step iii) using a deliming agent comprising a graft polymerization product of at least one of a polysaccharide, a polypeptide or a derivative thereof, wherein the polysaccharide derivative is an oxidatively, hydrolytically or enzymatically degradable polysaccharide, an oxidized hydrolytically degraded polysaccharide or an oxidized enzymatically degraded polysaccharide or a chemically modified degradation product of such a polysaccharide or a chemically modified monosaccharide, oligosaccharide or polysaccharide, and wherein the polypeptide derivative is a hydrolytically or enzymatically degraded and optionally chemically modified polypeptide, wherein the graft polymer product is obtained by free radical polymerization of: A) A monomer selected from the following monomers or a mixture of the following monomers (a) acrylic acid or methacrylic acid or a mixture thereof or an alkali metal salt, alkaline earth metal salt or ammonium salt thereof, and optionally at least one of (b) and (c), wherein (b) comprises other monoethylenically unsaturated monomers copolymerizable with monomer (a) and different from monomer (a), and wherein (c) comprising monomers having at least two ethylenically unsaturated non-conjugated double bonds in the molecule, If at least one of the following exists: B1) polysaccharides, oxidatively, hydrolytically or enzymatically degraded polysaccharides, oxidatively hydrolytically degraded polysaccharides or oxidatively enzymatically degraded polysaccharides or chemically modified degradation products of these, chemically modified monosaccharides, oligosaccharides or polysaccharides or mixtures of the compounds given, and B2) Polypeptides, hydrolytically or enzymatically degraded and optionally chemically modified polypeptides or mixtures of the given compounds.

15. Use of a graft polymer product for deliming hides and skins, wherein the graft polymer product comprises a graft polymer product of at least one of a polysaccharide, a polypeptide or a derivative thereof, wherein the derivative of the polysaccharide is an oxidatively, hydrolytically or enzymatically degradable polysaccharide, an oxidized hydrolytically degraded polysaccharide or an oxidized enzymatically degraded polysaccharide or a chemically modified degradation product of such a polysaccharide or a chemically modified monosaccharide, oligosaccharide or polysaccharide, and wherein the derivative of the polypeptide is a hydrolytically or enzymatically degraded and optionally chemically modified polypeptide, wherein the graft polymer product is obtained by free radical polymerization of: A) A monomer selected from the following monomers or a mixture of the following monomers (a) acrylic acid or methacrylic acid or a mixture thereof or an alkali metal salt, alkaline earth metal salt or ammonium salt thereof, and optionally at least one of (b) and (c), wherein (b) comprises other monoethylenically unsaturated monomers copolymerizable with monomer (a) and different from monomer (a), and wherein (c) comprising monomers having at least two ethylenically unsaturated non-conjugated double bonds in the molecule, If at least one of the following exists: B1) polysaccharides, oxidatively, hydrolytically or enzymatically degraded polysaccharides, oxidatively hydrolytically degraded polysaccharides or oxidatively enzymatically degraded polysaccharides or chemically modified degradation products of these, chemically modified monosaccharides, oligosaccharides or polysaccharides or mixtures of the compounds given, and B2) Polypeptides, hydrolytically or enzymatically degraded and optionally chemically modified polypeptides or mixtures of the given compounds.

16. A semi-finished product of a leather making process, which has been delimed with a graft polymer, wherein the graft polymer has a graft polymer of at least one of a polysaccharide, a polypeptide or a derivative thereof, wherein the derivative of the polysaccharide is an oxidatively, hydrolytically or enzymatically degraded polysaccharide, an oxidized hydrolytically degraded polysaccharide or an oxidized enzymatically degraded polysaccharide or a chemically modified degradation product of such a polysaccharide or a chemically modified monosaccharide, oligosaccharide or polysaccharide, and wherein the derivative of the polypeptide is a hydrolytically or enzymatically degraded and optionally chemically modified polypeptide, wherein the graft polymer is obtained by free radical polymerization of: A) A monomer selected from the following monomers or a mixture of the following monomers (a) acrylic acid or methacrylic acid or a mixture thereof or an alkali metal salt, alkaline earth metal salt or ammonium salt thereof, and optionally at least one of (b) and (c), wherein (b) comprises other monoethylenically unsaturated monomers copolymerizable with monomer (a) and different from monomer (a), and wherein (c) a monomer having at least two ethylenically unsaturated non-conjugated double bonds in the molecule, If at least one of the following exists: B1) polysaccharides, oxidatively, hydrolytically or enzymatically degraded polysaccharides, oxidatively hydrolytically degraded polysaccharides or oxidatively enzymatically degraded polysaccharides or chemically modified degradation products of these, chemically modified monosaccharides, oligosaccharides or polysaccharides or mixtures of the compounds given, and B2) Polypeptides, hydrolytically or enzymatically degraded and optionally chemically modified polypeptides or mixtures of the given compounds.

17. Leather which has been delimed with a graft polymer, wherein the graft polymer has a graft polymer of at least one of a polysaccharide, a polypeptide or a derivative thereof, wherein the derivative of the polysaccharide is an oxidatively, hydrolytically or enzymatically degraded polysaccharide, an oxidized hydrolytically degraded polysaccharide or an oxidized enzymatically degraded polysaccharide or a chemically modified degradation product of such or a chemically modified monosaccharide, oligosaccharide or polysaccharide, and wherein the derivative of the polypeptide is a hydrolytically or enzymatically degraded and optionally chemically modified polypeptide, wherein the graft polymer is obtained by free radical polymerization of: A) A monomer selected from the following monomers or a mixture of the following monomers (a) acrylic acid or methacrylic acid or a mixture thereof or an alkali metal salt, alkaline earth metal salt or ammonium salt thereof, and optionally at least one of (b) and (c), wherein (b) comprises other monoethylenically unsaturated monomers copolymerizable with monomer (a) and different from monomer (a), and wherein (c) a monomer having at least two ethylenically unsaturated non-conjugated double bonds in the molecule, If at least one of the following exists: B1) polysaccharides, oxidatively, hydrolytically or enzymatically degraded polysaccharides, oxidatively hydrolytically degraded polysaccharides or oxidatively enzymatically degraded polysaccharides or chemically modified degradation products of these, chemically modified monosaccharides, oligosaccharides or polysaccharides or mixtures of the compounds given, and B2) Polypeptides, hydrolytically or enzymatically degraded and optionally chemically modified polypeptides or mixtures of the given compounds.

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