Classifications

• • C—CHEMISTRY; METALLURGY
  • C14—SKINS; HIDES; PELTS; LEATHER
  • C14C—CHEMICAL TREATMENT OF HIDES, SKINS OR LEATHER, e.g. TANNING, IMPREGNATING, FINISHING; APPARATUS THEREFOR; COMPOSITIONS FOR TANNING
  • C14C3/00—Tanning; Compositions for tanning
  • C14C3/02—Chemical tanning
  • C14C3/08—Chemical tanning by organic agents
  • C14C3/16—Chemical tanning by organic agents using aliphatic aldehydes

Definitions

• the invention relates to a composition containing a tanning agent for tanning hides and / or skins. Furthermore, the invention also relates to a process for tanning hides and / or skins for the production of leather. In particular, the invention relates to a composition and a method for pretanning and / or retanning, preferably for pretanning.
• the tanning and, in particular, the pretanning of skins and / or skins by aldehydic tanning agents is well known and is used commercially, for example, in the so-called “wet white” process.
• the aldehydic tannins used here are predominantly formaldehyde, propionaldehyde, glyoxal and, in the most common cases, glutaraldehyde.
• a major disadvantage of these prior art compositions and processes based on the use of said tanning agents is that the tannins have too high reactivity towards the proteins of the skin to be tanned. Frequently, therefore, in particular with relatively thick hides and / or skins, insufficient penetration of the tanning agents into deeper skin layers of the skin to be tanned and / or the coat to be tanned may occur. This can lead to an inhomogeneous tanning, which can adversely affect the quality of the leather produced.
• aldehydic tanning agents in principle have a very high toxicity and a pungent odor.
• inhalation of aldehydic vapors and direct contact with these aldehydic tannins are often unavoidable in prior art compositions and methods based thereon, thus posing an increased health hazard to persons using them for tanning hides and / or skins.
• the above-mentioned components are at most 100% by weight or less, if the composition has other components than those mentioned above, the sum total of all components of the composition being 100% by weight each.
• composition according to the invention has the advantage over prior art compositions based on aldehydic tannins that acetals of aldehydic tannins are not or hardly reactive towards the proteins of the skin and / or skin to be tanned. Such acetals are stable especially in the neutral and alkaline medium and therefore do not react with the mentioned proteins when the Composition of the invention is applied at this pH to the skin and / or the coat. In addition, acetals of aldehyde tannins have lower toxicity than the aldehyde tannin itself, ie the aldehyde.
• composition according to the invention Another hitherto completely unknown, surprising effect is manifested in the composition according to the invention in that, when the composition according to the invention for tanning is used, improved penetration into deeper layers of the skin to be tanned and / or of the coat to be tanned can be achieved. In particular with relatively thick hides and skins, this makes it possible to achieve a more homogeneous tanning compared with previously known compositions based on aldehydic tannins.
• the pH value can be lowered after a contact time in such a way that the aldehydic tannin is released and thus becomes reactive.
• the aldehyde tannin can be fixed by increasing the pH and tanning can be stopped.
• the composition according to the invention is applied in non-reactive form to a skin and / or a coat, which is / are, for example, in a closable container.
• the aldehyde tannin of the composition can be activated, this being possible, for example, within the closed vessel by the addition of an acid.
• the composition of the invention may also be applied to a stained nakedness.
• Acetals also generally have a relatively poor shelf life. Surprisingly, it has now been found that the shelf life of the acetals used as ingredient in the composition described above by the mixture with a pH-regulating buffer component and / or with a solvent has already been significantly improved compared to a pure acetal. Thus, the composition of the invention over pure acetals has the advantage that it can be stored longer without causing undesirable reactions, by which aldehyde is released.
• the acetal of an aldehyde tanning agent is an acetal of formaldehyde, propionaldehyde, glutaraldehyde and / or glyoxal.
• the composition contains two or more of said acetals.
• the acetal is glutaraldehyde.
• the acetals of aldehydic tannins mentioned have a particularly good tanning effect.
• an alcohol component of the acetal of an aldehydic tanning agent is methanol, ethanol, diethylene glycol and / or triethylene glycol.
• the alcohol component of the acetal is methanol.
• Processes for the preparation of acetals of an aldehyde tanning agent are already known from the prior art. For example, in the US 2,885,443 and the US 4,448,977 Process for the preparation of an acetal, in particular glutaraldehyde described.
• the acetal of an aldehydic tanning agent prepared by previously known methods can also be obtained by the use of other previously known Purification methods, such as by column chromatography, in particular by flash chromatography, to obtain an even purer acetal.
• the composition according to the invention may have at least one saccharide, in particular a reducing saccharide.
• the composition according to the invention may comprise at least one saccharide having a dextrose equivalent of from 10 to 100.
• the proportion of the at least one saccharide in the composition is from 0.1% by weight to 30% by weight, in particular from 2.5% by weight to 15% by weight. , is.
• the composition comprises at least one or at least one, previously mentioned saccharide, which is selected from the group of glucose, sucrose or a mixture of glucose and sucrose. These are particularly suitable for tanning reducing saccharides that lead to improved tanning of a skin and / or a coat.
• the composition may be expedient for the composition to contain a proportion of polyoxaalkylene glycol.
• the proportion polyoxaalkylene glycol selected from the group consisting of polyoxaethylene diol, polyoxa-1,2-propylene diol or a mixture of polyoxyethylene diol and polyoxy-1,2-propylene diol.
• the composition contains two or more of said Polyoxaalkylenglycole.
• polyoxaalkylene glycol in the composition contains one or more polyoxaalkylene glycols having a molecular weight M R of 120 to 1,000. It may be particularly useful if one or the above-mentioned proportion of Polyoxaalkylenglycol / s in the composition is 2.5 to 15 wt .-%.
• composition according to the invention additionally contains an aldehyde, in particular wherein a proportion of the aldehyde in the composition is from 0.1% by weight to 50% by weight, in particular from 5% by weight to 50% by weight. , in particular 10 wt .-% to 40 wt .-%, in particular 20 wt .-% to 30 wt .-%, is.
• the solvent of the composition of the present invention may have one selected from the group consisting of water, water-soluble organic solvents or a mixture of water and water-soluble organic solvents.
• suitable water-soluble organic solvents are glycerol and / or a monoetherified polyoxaalkylene glycol.
• the water-soluble organic solvent has a molecular weight M R of greater than or equal to 100 and / or of less than or equal to 2,000.
• composition according to the invention can be adjusted by the pH-regulating buffer component, a pH of the composition of 7.5 to 10.5.
• the aldehyde tannin is stable and therefore unreactive with the proteins of the skin to be tanned and / or the coat to be tanned.
• a particularly good penetration of the composition into deeper layers can be achieved.
• Suitable pH-regulating buffer components may be, for example, one or more selected from the group consisting of carbonate buffer, borate buffer and / or phosphate buffer.
• the same advantages as previously explained for the composition according to the invention apply.
• the method according to the invention can be used for the tanning, pretanning and / or retanning of a nakedness.
• a pelage a fleshed and / or depilated skin can be defined after the pimple and / or the stain, which, however, has not yet been tanned.
• an acetal of formaldehyde, propionaldehyde, glutaraldehyde, glyoxal and / or one according to formula A and / or formula B can be used as the acetal of an aldehydic tanning agent.
• a particularly good tanning can be achieved by using methanol, ethanol, diethylene glycol and / or triethylene glycol as an alcohol component of the acetal or two or more of the alcohol components mentioned.
• methanol ethanol, diethylene glycol and / or triethylene glycol
• an alcohol component of the acetal or two or more of the alcohol components mentioned may be provided as an alcohol component methanol.
• the acetal is added with a composition comprising further components. Alternatively or additionally, it may be particularly useful if the acetal is added with the composition of the invention as described and claimed herein.
• a particularly good tanning effect can be achieved if a proportion of the added acetal based on a total weight of the coat and / or the skin 0.25 wt .-% to 10 wt .-%, in particular 1.0 wt .-% to 6 , 0 wt .-%, in particular 1.5 wt .-% to 5 wt .-%, preferably 2.0 wt .-% or 4.5 wt .-%, is.
• the pH is adjusted to 6 to 9, in particular to 7.5 to 8.5, before the addition of the acetal.
• the aldehyde tannin is not released, leaving the acetal stable. Therefore, the aldehyde tannin can not (yet) react with the proteins of the skin and / or the coat.
• the addition of the acetal is carried out after performing a pickling process and / or after performing a pickling step.
• the skin and / or coat may be treated with an acid and / or saline.
• pickling and pickling steps are already known from the prior art.
• the aldehydic tanning agent For the release of the aldehydic tanning agent it may be provided that, after the addition of the acetal into the liquor, the pH of the liquor is adjusted to 1 to 2.5, in particular to 1.8 to 2.5. After release of the aldehydic tannin, it can react with the proteins of the skin to be tanned and / or the coat to be tanned.
• acetals provided for tanning are provided in the composition according to the invention and / or the process according to the invention in combination with other tanning agents. Suitable further tanning agents for this purpose are mentioned below in the examples.
• the invention also relates to a leather produced by the method according to the invention as described and claimed herein and / or by the use of the composition according to the invention as described and claimed herein is.
• the leather according to the invention may be a pretanned leather.
• the invention also relates to the use of the abovementioned leather according to the invention for producing a ground and / or full-grain Crust leather by one or more steps selected from the group of retanning, fatliquoring, filling and / or coloring.
• the invention therefore also relates to a Crust leather, in particular a ground and / or full-grain Crust leather, produced by the inventive treatment of the leather, as mentioned above, by one or more of the steps selected from the group of retanning, fatliquoring, filling and / or staining.
• the invention further relates to the use of the leather according to the invention, as described and claimed herein and / or crust leather according to the invention, as described and claimed herein, for the production of dressed leather, in particular for the production of an automobile, furniture, clothing, glove , Leather goods, aircraft, lining and / or shoe upper leather article.
• the invention thus relates to a composition comprising an acetal of an aldehydic tanning agent for the tanning of hides and / or skins and to a process for the tanning of hides and / or skins for the production of leather, wherein an acetal of an aldehyde tanning agent is used.
• an aldehyde tanning agent By lowering the pH, the aldehyde tannin can be released, thereby initiating a tanning step.
• the composition according to the invention and the method according to the invention are characterized by a lower toxicity compared to conventional ones Compositions and tanning methods based on aldehydic tannins. Furthermore, an improved penetration of the tanning agents into deeper layers of the skin and / or the coat is possible, so that a particularly homogeneous tanning is achieved.
• Acetals of aldehydic tannins can be used for the pretanning and / or retanning of hides, especially animal skins, and / or skins, such as those derived from bovine, porcine, goat, venison, Sheep and / or deer can come from.
• acetals of aldehydic tannins and their use as described and claimed herein can also be used for the pretanning and / or retanning of hides, in particular animal skins and / or hides, which have been pretreated by known, conventional methods.
• Suitable methods for pretreatment may be, for example, liming, deliming, pickling, pimpling and / or mechanical treatment.
• the process according to the invention for the pretanning, (main) tanning and / or retanning of hides, in particular animal skins, and / or hides, as described and claimed herein, can be carried out in an aqueous medium, in particular in an aqueous liquor.
• the pH value can be adjusted to values of 1 to 10.
• a suitable temperature for carrying out the process according to the invention may be between 10 ° C and 50 ° C.
• the temperature is preferably between 15 ° C and 35 ° C, especially at 25 ° C.
• a suitable duration of the actual tanning step that is, an incubation period of the skins and / or the skins with the released aldehyde (corresponding to the aldehyde tannin) may be from 10 minutes to 12 hours.
• a skin to be tanned and / or a coat to be tanned may be provided in a conventional tanning vessel. All further steps of the method according to the invention can then be carried out, for example, in this vessel and / or a drum.
• tanning agents for the pretanning and / or retanning of hides, in particular animal skins, and / or skins
• suitable further tanning agents may be mineral tanning agents, such as chromium, aluminum, zirconium, titanium and iron salts, synthetic tanning agents (syntans), polymer tanning agents and / or vegetable tanning agents (vegetable tanning agents).
• weight percentages in the following specific examples are based on a total weight of the skin to be tanned and / or the coat to be tanned.
• the skin to be tanned and / or the coat to be tanned are provided in 3000 ml of water (hereinafter referred to as aqueous liquor) having a pH of 7.5 to 8.5 and a temperature of 25 ° C. in a suitable vessel ,
• an acetal of an aldehydic tanning agent for example acetal of glutaraldehyde
• acetal was here, as it was in US 2,885,443 and or US 4,448,977 described.
• the liquor with the acetal is allowed to act on the skin and / or the coat, for example in a rotatable drum provided therefor.
• An exposure time can be chosen freely, for example, depending on the thickness of the skin and / or the coat. The thicker a skin and / or fur, the longer the exposure time should be chosen to achieve adequate penetration of the acetal into deeper skin layers. For example, the exposure time can be between 2 hours and 7 hours. A preferred exposure time is 5 hours.
• 2% by weight of formic acid are added and the pH is adjusted to 1.8 to 2.5.
• the pH of the aldehyde tannin for example in the form of glutaraldehyde, released.
• the released aldehydic tannin can then react with the proteins of the skin and / or coat, in particular with collagen. This initiates the actual tanning process.
• the released aldehyde is allowed to act on the skin and / or fur in a tanning step, for example in the rotatable drum.
• a suitable exposure time can be between 1.5 hours and 5 hours, preferably 3 hours.
• 2% by weight of sodium bicarbonate are added.
• the aqueous liquor is allowed to act on the pre-tanned skin and / or the pre-tanned coat in order to fix the aldehyde as completely as possible.
• An exposure time can be, for example, between 1.5 and 4.5 hours, in particular 3 hours.
• the pH is then adjusted to 4.0 to 4.2.
• the liquor is discarded and the pre-tanned skin and / or the pre-tanned coat with water, especially with about 3000 mL of water.
• the pre-tanned skin and / or the pre-tanned coat can be dried and brought to a thickness of 1.1 to 1.3 mm, for example.
• the skin to be tanned and / or the coat to be tanned are provided in 3000 ml of water (hereinafter referred to as aqueous liquor) having a pH of 3.0 to 3.2 and a temperature of 25 ° C in a suitable vessel ,
• aqueous liquor 3000 ml of water having a pH of 3.0 to 3.2 and a temperature of 25 ° C in a suitable vessel
• no penetration step is provided in which the aldehydic tanning agent in the form of the acetal first acts on the skin and / or the coat without reacting with proteins.
• an acetal of an aldehydic tanning agent for example acetal of glutaraldehyde
• an aldehydic tanning agent for example acetal of glutaraldehyde
• the liquor is discarded and the pre-tanned skin and / or the pre-tanned coat with water, especially with about 3000 mL of water.
• the pre-tanned skin and / or the pre-tanned coat can be dried and brought to a thickness of 1.1 to 1.3 mm, for example.

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• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Treatment And Processing Of Natural Fur Or Leather (AREA)

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• 2016
  • 2016-04-06 DE DE102016004192.7A patent/DE102016004192A1/de not_active Withdrawn
• 2017
  • 2017-03-29 EP EP19167730.1A patent/EP3561081A1/fr not_active Withdrawn
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